diff --git a/mesonbuild/build.py b/mesonbuild/build.py
index 5f5dd6b38..9837d5a8d 100644
--- a/mesonbuild/build.py
+++ b/mesonbuild/build.py
@@ -20,7 +20,7 @@ from . import environment
 from . import dependencies
 from . import mlog
 from .mesonlib import File, MesonException, listify, extract_as_list
-from .mesonlib import flatten, typeslistify, stringlistify, classify_unity_sources
+from .mesonlib import typeslistify, stringlistify, classify_unity_sources
 from .mesonlib import get_filenames_templates_dict, substitute_values
 from .environment import for_windows, for_darwin, for_cygwin
 from .compilers import is_object, clike_langs, sort_clike, lang_suffixes
@@ -682,7 +682,7 @@ class BuildTarget(Target):
             if 'd' in self.compilers:
                 self.add_compiler_args('d', self.compilers['d'].get_feature_args(dfeatures))
 
-        self.link_args = flatten(kwargs.get('link_args', []))
+        self.link_args = extract_as_list(kwargs, 'link_args')
         for i in self.link_args:
             if not isinstance(i, str):
                 raise InvalidArguments('Link_args arguments must be strings.')
@@ -856,9 +856,7 @@ You probably should put it in link_with instead.''')
         return self.external_deps
 
     def link(self, target):
-        for t in flatten(target):
-            if hasattr(t, 'held_object'):
-                t = t.held_object
+        for t in listify(target, unholder=True):
             if not t.is_linkable_target():
                 raise InvalidArguments('Link target {!r} is not linkable.'.format(t))
             if isinstance(self, SharedLibrary) and isinstance(t, StaticLibrary) and not t.pic:
@@ -870,9 +868,7 @@ You probably should put it in link_with instead.''')
             self.link_targets.append(t)
 
     def link_whole(self, target):
-        for t in flatten(target):
-            if hasattr(t, 'held_object'):
-                t = t.held_object
+        for t in listify(target, unholder=True):
             if not isinstance(t, StaticLibrary):
                 raise InvalidArguments('{!r} is not a static library.'.format(t))
             if isinstance(self, SharedLibrary) and not t.pic:
@@ -915,7 +911,7 @@ You probably should put it in link_with instead.''')
         self.include_dirs += ids
 
     def add_compiler_args(self, language, args):
-        args = flatten(args)
+        args = listify(args)
         for a in args:
             if not isinstance(a, (str, File)):
                 raise InvalidArguments('A non-string passed to compiler args.')
@@ -1546,11 +1542,9 @@ class CustomTarget(Target):
         return deps
 
     def flatten_command(self, cmd):
-        cmd = listify(cmd)
+        cmd = listify(cmd, unholder=True)
         final_cmd = []
         for c in cmd:
-            if hasattr(c, 'held_object'):
-                c = c.held_object
             if isinstance(c, str):
                 final_cmd.append(c)
             elif isinstance(c, File):
@@ -1573,12 +1567,7 @@ class CustomTarget(Target):
 
     def process_kwargs(self, kwargs):
         super().process_kwargs(kwargs)
-        sources = flatten(kwargs.get('input', []))
-        self.sources = []
-        for s in sources:
-            if hasattr(s, 'held_object'):
-                s = s.held_object
-            self.sources.append(s)
+        self.sources = extract_as_list(kwargs, 'input', unholder=True)
         if 'output' not in kwargs:
             raise InvalidArguments('Missing keyword argument "output".')
         self.outputs = listify(kwargs['output'])
diff --git a/mesonbuild/dependencies/base.py b/mesonbuild/dependencies/base.py
index 7c7f986f0..0d9742d42 100644
--- a/mesonbuild/dependencies/base.py
+++ b/mesonbuild/dependencies/base.py
@@ -23,7 +23,7 @@ from enum import Enum
 
 from .. import mlog
 from .. import mesonlib
-from ..mesonlib import MesonException, Popen_safe, flatten, version_compare_many, listify
+from ..mesonlib import MesonException, Popen_safe, version_compare_many, listify
 
 
 # These must be defined in this file to avoid cyclical references.
@@ -586,7 +586,7 @@ class ExtraFrameworkDependency(ExternalDependency):
 
 def get_dep_identifier(name, kwargs, want_cross):
     # Need immutable objects since the identifier will be used as a dict key
-    version_reqs = flatten(kwargs.get('version', []))
+    version_reqs = listify(kwargs.get('version', []))
     if isinstance(version_reqs, list):
         version_reqs = frozenset(version_reqs)
     identifier = (name, version_reqs, want_cross)
@@ -599,7 +599,7 @@ def get_dep_identifier(name, kwargs, want_cross):
             continue
         # All keyword arguments are strings, ints, or lists (or lists of lists)
         if isinstance(value, list):
-            value = frozenset(flatten(value))
+            value = frozenset(listify(value))
         identifier += (key, value)
     return identifier
 
diff --git a/mesonbuild/dependencies/dev.py b/mesonbuild/dependencies/dev.py
index d2dd1075e..387300a37 100644
--- a/mesonbuild/dependencies/dev.py
+++ b/mesonbuild/dependencies/dev.py
@@ -21,7 +21,7 @@ import shutil
 
 from .. import mlog
 from .. import mesonlib
-from ..mesonlib import version_compare, Popen_safe
+from ..mesonlib import version_compare, Popen_safe, stringlistify, extract_as_list
 from .base import DependencyException, ExternalDependency, PkgConfigDependency
 
 class GTestDependency(ExternalDependency):
@@ -185,7 +185,7 @@ class LLVMDependency(ExternalDependency):
             raise DependencyException('Could not generate modules for LLVM.')
         self.modules = shlex.split(out)
 
-        modules = mesonlib.stringlistify(mesonlib.flatten(kwargs.get('modules', [])))
+        modules = stringlistify(extract_as_list(kwargs, 'modules'))
         for mod in sorted(set(modules)):
             if mod not in self.modules:
                 mlog.log('LLVM module', mod, 'found:', mlog.red('NO'))
diff --git a/mesonbuild/interpreter.py b/mesonbuild/interpreter.py
index 7641514d0..b9380807b 100644
--- a/mesonbuild/interpreter.py
+++ b/mesonbuild/interpreter.py
@@ -48,6 +48,14 @@ def stringifyUserArguments(args):
     raise InvalidArguments('Function accepts only strings, integers, lists and lists thereof.')
 
 
+class ObjectHolder:
+    def __init__(self, obj):
+        self.held_object = obj
+
+    def __repr__(self):
+        return '<Holder: {!r}>'.format(self.held_object)
+
+
 class TryRunResultHolder(InterpreterObject):
     def __init__(self, res):
         super().__init__()
@@ -117,17 +125,18 @@ class RunProcess(InterpreterObject):
     def stderr_method(self, args, kwargs):
         return self.stderr
 
-class ConfigureFileHolder(InterpreterObject):
+class ConfigureFileHolder(InterpreterObject, ObjectHolder):
 
     def __init__(self, subdir, sourcename, targetname, configuration_data):
         InterpreterObject.__init__(self)
-        self.held_object = build.ConfigureFile(subdir, sourcename, targetname, configuration_data)
+        ObjectHolder.__init__(self, build.ConfigureFile(subdir, sourcename,
+                                                        targetname, configuration_data))
 
 
-class EnvironmentVariablesHolder(MutableInterpreterObject):
+class EnvironmentVariablesHolder(MutableInterpreterObject, ObjectHolder):
     def __init__(self):
-        super().__init__()
-        self.held_object = build.EnvironmentVariables()
+        MutableInterpreterObject.__init__(self)
+        ObjectHolder.__init__(self, build.EnvironmentVariables())
         self.methods.update({'set': self.set_method,
                              'append': self.append_method,
                              'prepend': self.prepend_method,
@@ -158,11 +167,11 @@ class EnvironmentVariablesHolder(MutableInterpreterObject):
         self.add_var(self.held_object.prepend, args, kwargs)
 
 
-class ConfigurationDataHolder(MutableInterpreterObject):
+class ConfigurationDataHolder(MutableInterpreterObject, ObjectHolder):
     def __init__(self):
-        super().__init__()
+        MutableInterpreterObject.__init__(self)
         self.used = False # These objects become immutable after use in configure_file.
-        self.held_object = build.ConfigurationData()
+        ObjectHolder.__init__(self, build.ConfigurationData())
         self.methods.update({'set': self.set_method,
                              'set10': self.set10_method,
                              'set_quoted': self.set_quoted_method,
@@ -242,10 +251,10 @@ class ConfigurationDataHolder(MutableInterpreterObject):
 # Interpreter objects can not be pickled so we must have
 # these wrappers.
 
-class DependencyHolder(InterpreterObject):
+class DependencyHolder(InterpreterObject, ObjectHolder):
     def __init__(self, dep):
         InterpreterObject.__init__(self)
-        self.held_object = dep
+        ObjectHolder.__init__(self, dep)
         self.methods.update({'found': self.found_method,
                              'type_name': self.type_name_method,
                              'version': self.version_method,
@@ -272,10 +281,10 @@ class DependencyHolder(InterpreterObject):
             raise InterpreterException('Variable name must be a string.')
         return self.held_object.get_pkgconfig_variable(varname)
 
-class InternalDependencyHolder(InterpreterObject):
+class InternalDependencyHolder(InterpreterObject, ObjectHolder):
     def __init__(self, dep):
         InterpreterObject.__init__(self)
-        self.held_object = dep
+        ObjectHolder.__init__(self, dep)
         self.methods.update({'found': self.found_method,
                              'version': self.version_method,
                              })
@@ -286,10 +295,10 @@ class InternalDependencyHolder(InterpreterObject):
     def version_method(self, args, kwargs):
         return self.held_object.get_version()
 
-class ExternalProgramHolder(InterpreterObject):
+class ExternalProgramHolder(InterpreterObject, ObjectHolder):
     def __init__(self, ep):
         InterpreterObject.__init__(self)
-        self.held_object = ep
+        ObjectHolder.__init__(self, ep)
         self.methods.update({'found': self.found_method,
                              'path': self.path_method})
 
@@ -308,10 +317,10 @@ class ExternalProgramHolder(InterpreterObject):
     def get_name(self):
         return self.held_object.get_name()
 
-class ExternalLibraryHolder(InterpreterObject):
+class ExternalLibraryHolder(InterpreterObject, ObjectHolder):
     def __init__(self, el):
         InterpreterObject.__init__(self)
-        self.held_object = el
+        ObjectHolder.__init__(self, el)
         self.methods.update({'found': self.found_method})
 
     def found(self):
@@ -332,11 +341,11 @@ class ExternalLibraryHolder(InterpreterObject):
     def get_exe_args(self):
         return self.held_object.get_exe_args()
 
-class GeneratorHolder(InterpreterObject):
+class GeneratorHolder(InterpreterObject, ObjectHolder):
     def __init__(self, interpreter, args, kwargs):
-        super().__init__()
+        InterpreterObject.__init__(self)
         self.interpreter = interpreter
-        self.held_object = build.Generator(args, kwargs)
+        ObjectHolder.__init__(self, build.Generator(args, kwargs))
         self.methods.update({'process': self.process_method})
 
     def process_method(self, args, kwargs):
@@ -345,13 +354,13 @@ class GeneratorHolder(InterpreterObject):
         return GeneratedListHolder(gl)
 
 
-class GeneratedListHolder(InterpreterObject):
+class GeneratedListHolder(InterpreterObject, ObjectHolder):
     def __init__(self, arg1, extra_args=[]):
-        super().__init__()
+        InterpreterObject.__init__(self)
         if isinstance(arg1, GeneratorHolder):
-            self.held_object = build.GeneratedList(arg1.held_object, extra_args)
+            ObjectHolder.__init__(self, build.GeneratedList(arg1.held_object, extra_args))
         else:
-            self.held_object = arg1
+            ObjectHolder.__init__(self, arg1)
 
     def __repr__(self):
         r = '<{}: {!r}>'
@@ -360,14 +369,15 @@ class GeneratedListHolder(InterpreterObject):
     def add_file(self, a):
         self.held_object.add_file(a)
 
-class BuildMachine(InterpreterObject):
+class BuildMachine(InterpreterObject, ObjectHolder):
     def __init__(self, compilers):
         self.compilers = compilers
         InterpreterObject.__init__(self)
-        self.held_object = environment.MachineInfo(environment.detect_system(),
-                                                   environment.detect_cpu_family(self.compilers),
-                                                   environment.detect_cpu(self.compilers),
-                                                   sys.byteorder)
+        held_object = environment.MachineInfo(environment.detect_system(),
+                                              environment.detect_cpu_family(self.compilers),
+                                              environment.detect_cpu(self.compilers),
+                                              sys.byteorder)
+        ObjectHolder.__init__(self, held_object)
         self.methods.update({'system': self.system_method,
                              'cpu_family': self.cpu_family_method,
                              'cpu': self.cpu_method,
@@ -388,7 +398,7 @@ class BuildMachine(InterpreterObject):
 
 # This class will provide both host_machine and
 # target_machine
-class CrossMachineInfo(InterpreterObject):
+class CrossMachineInfo(InterpreterObject, ObjectHolder):
     def __init__(self, cross_info):
         InterpreterObject.__init__(self)
         minimum_cross_info = {'cpu', 'cpu_family', 'endian', 'system'}
@@ -397,10 +407,11 @@ class CrossMachineInfo(InterpreterObject):
                 'Machine info is currently {}\n'.format(cross_info) +
                 'but is missing {}.'.format(minimum_cross_info - set(cross_info)))
         self.info = cross_info
-        self.held_object = environment.MachineInfo(cross_info['system'],
-                                                   cross_info['cpu_family'],
-                                                   cross_info['cpu'],
-                                                   cross_info['endian'])
+        minfo = environment.MachineInfo(cross_info['system'],
+                                        cross_info['cpu_family'],
+                                        cross_info['cpu'],
+                                        cross_info['endian'])
+        ObjectHolder.__init__(self, minfo)
         self.methods.update({'system': self.system_method,
                              'cpu': self.cpu_method,
                              'cpu_family': self.cpu_family_method,
@@ -419,10 +430,10 @@ class CrossMachineInfo(InterpreterObject):
     def endian_method(self, args, kwargs):
         return self.held_object.endian
 
-class IncludeDirsHolder(InterpreterObject):
+class IncludeDirsHolder(InterpreterObject, ObjectHolder):
     def __init__(self, idobj):
-        super().__init__()
-        self.held_object = idobj
+        InterpreterObject.__init__(self)
+        ObjectHolder.__init__(self, idobj)
 
 class Headers(InterpreterObject):
 
@@ -447,10 +458,10 @@ class Headers(InterpreterObject):
     def get_custom_install_dir(self):
         return self.custom_install_dir
 
-class DataHolder(InterpreterObject):
+class DataHolder(InterpreterObject, ObjectHolder):
     def __init__(self, data):
-        super().__init__()
-        self.held_object = data
+        InterpreterObject.__init__(self)
+        ObjectHolder.__init__(self, data)
 
     def get_source_subdir(self):
         return self.held_object.source_subdir
@@ -495,20 +506,20 @@ class Man(InterpreterObject):
     def get_sources(self):
         return self.sources
 
-class GeneratedObjectsHolder(InterpreterObject):
+class GeneratedObjectsHolder(InterpreterObject, ObjectHolder):
     def __init__(self, held_object):
-        super().__init__()
-        self.held_object = held_object
+        InterpreterObject.__init__(self)
+        ObjectHolder.__init__(self, held_object)
 
-class TargetHolder(InterpreterObject):
-    def __init__(self):
-        super().__init__()
+class TargetHolder(InterpreterObject, ObjectHolder):
+    def __init__(self, target, interp):
+        InterpreterObject.__init__(self)
+        ObjectHolder.__init__(self, target)
+        self.interpreter = interp
 
 class BuildTargetHolder(TargetHolder):
     def __init__(self, target, interp):
-        super().__init__()
-        self.held_object = target
-        self.interpreter = interp
+        super().__init__(target, interp)
         self.methods.update({'extract_objects': self.extract_objects_method,
                              'extract_all_objects': self.extract_all_objects_method,
                              'get_id': self.get_id_method,
@@ -566,16 +577,14 @@ class JarHolder(BuildTargetHolder):
     def __init__(self, target, interp):
         super().__init__(target, interp)
 
-class CustomTargetIndexHolder(InterpreterObject):
+class CustomTargetIndexHolder(InterpreterObject, ObjectHolder):
     def __init__(self, object_to_hold):
-        super().__init__()
-        self.held_object = object_to_hold
+        InterpreterObject.__init__(self)
+        ObjectHolder.__init__(self, object_to_hold)
 
 class CustomTargetHolder(TargetHolder):
-    def __init__(self, object_to_hold, interp):
-        super().__init__()
-        self.held_object = object_to_hold
-        self.interpreter = interp
+    def __init__(self, target, interp):
+        super().__init__(target, interp)
         self.methods.update({'full_path': self.full_path_method,
                              })
 
@@ -596,10 +605,10 @@ class CustomTargetHolder(TargetHolder):
     def __delitem__(self, index):
         raise InterpreterException('Cannot delete a member of a CustomTarget')
 
-class RunTargetHolder(InterpreterObject):
+class RunTargetHolder(InterpreterObject, ObjectHolder):
     def __init__(self, name, command, args, dependencies, subdir):
-        super().__init__()
-        self.held_object = build.RunTarget(name, command, args, dependencies, subdir)
+        InterpreterObject.__init__(self)
+        ObjectHolder.__init__(self, build.RunTarget(name, command, args, dependencies, subdir))
 
     def __repr__(self):
         r = '<{} {}: {}>'
@@ -625,11 +634,11 @@ class Test(InterpreterObject):
     def get_name(self):
         return self.name
 
-class SubprojectHolder(InterpreterObject):
+class SubprojectHolder(InterpreterObject, ObjectHolder):
 
     def __init__(self, subinterpreter):
-        super().__init__()
-        self.held_object = subinterpreter
+        InterpreterObject.__init__(self)
+        ObjectHolder.__init__(self, subinterpreter)
         self.methods.update({'get_variable': self.get_variable_method,
                              })
 
@@ -1056,11 +1065,11 @@ ModuleState = namedtuple('ModuleState', [
     'man', 'global_args', 'project_args', 'build_machine', 'host_machine',
     'target_machine'])
 
-class ModuleHolder(InterpreterObject):
+class ModuleHolder(InterpreterObject, ObjectHolder):
     def __init__(self, modname, module, interpreter):
         InterpreterObject.__init__(self)
+        ObjectHolder.__init__(self, module)
         self.modname = modname
-        self.held_object = module
         self.interpreter = interpreter
 
     def method_call(self, method_name, args, kwargs):
@@ -1551,12 +1560,11 @@ class Interpreter(InterpreterBase):
         version = kwargs.get('version', self.project_version)
         if not isinstance(version, str):
             raise InterpreterException('Version must be a string.')
-        incs = extract_as_list(kwargs, 'include_directories')
-        libs = extract_as_list(kwargs, 'link_with')
+        incs = extract_as_list(kwargs, 'include_directories', unholder=True)
+        libs = extract_as_list(kwargs, 'link_with', unholder=True)
         sources = extract_as_list(kwargs, 'sources')
-        sources = self.source_strings_to_files(self.flatten(sources))
-        deps = self.flatten(kwargs.get('dependencies', []))
-        deps = listify(deps)
+        sources = listify(self.source_strings_to_files(sources), unholder=True)
+        deps = extract_as_list(kwargs, 'dependencies', unholder=True)
         compile_args = mesonlib.stringlistify(kwargs.get('compile_args', []))
         link_args = mesonlib.stringlistify(kwargs.get('link_args', []))
         final_deps = []
@@ -1568,13 +1576,8 @@ class Interpreter(InterpreterBase):
             if not isinstance(d, (dependencies.Dependency, dependencies.ExternalLibrary, dependencies.InternalDependency)):
                 raise InterpreterException('Dependencies must be external deps')
             final_deps.append(d)
-        dep = dependencies.InternalDependency(version,
-                                              mesonlib.unholder_array(incs),
-                                              compile_args,
-                                              link_args,
-                                              mesonlib.unholder_array(libs),
-                                              mesonlib.unholder_array(sources),
-                                              final_deps)
+        dep = dependencies.InternalDependency(version, incs, compile_args,
+                                              link_args, libs, sources, final_deps)
         return DependencyHolder(dep)
 
     @noKwargs
@@ -1629,7 +1632,7 @@ class Interpreter(InterpreterBase):
                                            'or not executable'.format(cmd))
             cmd = prog
         expanded_args = []
-        for a in mesonlib.flatten(cargs):
+        for a in listify(cargs):
             if isinstance(a, str):
                 expanded_args.append(a)
             elif isinstance(a, mesonlib.File):
@@ -2299,11 +2302,7 @@ to directly access options of other subprojects.''')
             raise InterpreterException('Run_target needs at least one positional argument.')
 
         cleaned_args = []
-        for i in mesonlib.flatten(all_args):
-            try:
-                i = i.held_object
-            except AttributeError:
-                pass
+        for i in listify(all_args, unholder=True):
             if not isinstance(i, (str, build.BuildTarget, build.CustomTarget, dependencies.ExternalProgram, mesonlib.File)):
                 mlog.debug('Wrong type:', str(i))
                 raise InterpreterException('Invalid argument to run_target.')
@@ -2374,11 +2373,10 @@ to directly access options of other subprojects.''')
         par = kwargs.get('is_parallel', True)
         if not isinstance(par, bool):
             raise InterpreterException('Keyword argument is_parallel must be a boolean.')
-        cmd_args = extract_as_list(kwargs, 'args')
+        cmd_args = extract_as_list(kwargs, 'args', unholder=True)
         for i in cmd_args:
-            if not isinstance(i, (str, mesonlib.File, TargetHolder)):
+            if not isinstance(i, (str, mesonlib.File, build.Target)):
                 raise InterpreterException('Command line arguments must be strings, files or targets.')
-        cmd_args = mesonlib.unholder_array(cmd_args)
         env = self.unpack_env_kwarg(kwargs)
         should_fail = kwargs.get('should_fail', False)
         if not isinstance(should_fail, bool):
@@ -2796,7 +2794,8 @@ different subdirectory.
             elif isinstance(s, str):
                 s = mesonlib.File.from_source_file(self.environment.source_dir, self.subdir, s)
             else:
-                raise InterpreterException("Source item is not string or File-type object.")
+                raise InterpreterException('Source item is {!r} instead of '
+                                           'string or File-type object'.format(s))
             results.append(s)
         return results
 
@@ -2822,7 +2821,7 @@ different subdirectory.
         if not args:
             raise InterpreterException('Target does not have a name.')
         name = args[0]
-        sources = args[1:]
+        sources = listify(args[1:])
         if self.environment.is_cross_build():
             if kwargs.get('native', False):
                 is_cross = False
@@ -2830,19 +2829,14 @@ different subdirectory.
                 is_cross = True
         else:
             is_cross = False
-        try:
-            kw_src = self.flatten(kwargs['sources'])
-            kw_src = listify(kw_src)
-        except KeyError:
-            kw_src = []
-        sources += kw_src
+        if 'sources' in kwargs:
+            sources += listify(kwargs['sources'])
         sources = self.source_strings_to_files(sources)
-        objs = self.flatten(kwargs.get('objects', []))
-        kwargs['dependencies'] = self.flatten(kwargs.get('dependencies', []))
+        objs = extract_as_list(kwargs, 'objects')
+        kwargs['dependencies'] = extract_as_list(kwargs, 'dependencies')
         if 'extra_files' in kwargs:
             ef = extract_as_list(kwargs, 'extra_files')
             kwargs['extra_files'] = self.source_strings_to_files(ef)
-        objs = listify(objs)
         self.check_sources_exist(os.path.join(self.source_root, self.subdir), sources)
         if targetholder is ExecutableHolder:
             targetclass = build.Executable
diff --git a/mesonbuild/mesonlib.py b/mesonbuild/mesonlib.py
index 71134a8a9..5c4c3747b 100644
--- a/mesonbuild/mesonlib.py
+++ b/mesonbuild/mesonlib.py
@@ -199,17 +199,6 @@ def classify_unity_sources(compilers, sources):
             compsrclist[comp].append(src)
     return compsrclist
 
-def flatten(item):
-    if not isinstance(item, list):
-        return [item]
-    result = []
-    for i in item:
-        if isinstance(i, list):
-            result += flatten(i)
-        else:
-            result.append(i)
-    return result
-
 def is_osx():
     return platform.system().lower() == 'darwin'
 
@@ -474,24 +463,45 @@ def replace_if_different(dst, dst_tmp):
     else:
         os.unlink(dst_tmp)
 
-
-def listify(*args):
+def listify(item, flatten=True, unholder=False):
     '''
-    Returns a list with all args embedded in a list if they are not of type list.
+    Returns a list with all args embedded in a list if they are not a list.
     This function preserves order.
+    @flatten: Convert lists of lists to a flat list
+    @unholder: Replace each item with the object it holds, if required
+
+    Note: unholding only works recursively when flattening
     '''
-    if len(args) == 1:  # Special case with one single arg
-        return args[0] if type(args[0]) is list else [args[0]]
-    return [item if type(item) is list else [item] for item in args]
+    if not isinstance(item, list):
+        if unholder and hasattr(item, 'held_object'):
+            item = item.held_object
+        return [item]
+    result = []
+    for i in item:
+        if unholder and hasattr(i, 'held_object'):
+            i = i.held_object
+        if flatten and isinstance(i, list):
+            result += listify(i, flatten=True, unholder=unholder)
+        else:
+            result.append(i)
+    return result
 
 
-def extract_as_list(dict_object, *keys, pop = False):
+def extract_as_list(dict_object, *keys, pop=False, **kwargs):
     '''
     Extracts all values from given dict_object and listifies them.
     '''
+    result = []
+    fetch = dict_object.get
     if pop:
-        return listify(*[dict_object.pop(key, []) for key in keys])
-    return listify(*[dict_object.get(key, []) for key in keys])
+        fetch = dict_object.pop
+    # If there's only one key, we don't return a list with one element
+    if len(keys) == 1:
+        return listify(fetch(keys[0], []), **kwargs)
+    # Return a list of values corresponding to *keys
+    for key in keys:
+        result.append(listify(fetch(key, []), **kwargs))
+    return result
 
 
 def typeslistify(item, types):
@@ -750,15 +760,6 @@ def windows_proof_rmtree(f):
     # Try one last time and throw if it fails.
     shutil.rmtree(f)
 
-def unholder_array(entries):
-    result = []
-    entries = flatten(entries)
-    for e in entries:
-        if hasattr(e, 'held_object'):
-            e = e.held_object
-        result.append(e)
-    return result
-
 class OrderedSet(collections.MutableSet):
     """A set that preserves the order in which items are added, by first
     insertion.
diff --git a/mesonbuild/modules/gnome.py b/mesonbuild/modules/gnome.py
index fa2bbb4f1..1f813da92 100644
--- a/mesonbuild/modules/gnome.py
+++ b/mesonbuild/modules/gnome.py
@@ -20,7 +20,7 @@ import os
 import copy
 import subprocess
 from . import ModuleReturnValue
-from ..mesonlib import MesonException, OrderedSet, Popen_safe
+from ..mesonlib import MesonException, OrderedSet, Popen_safe, extract_as_list
 from ..dependencies import Dependency, PkgConfigDependency, InternalDependency
 from .. import mlog
 from .. import mesonlib
@@ -323,11 +323,9 @@ class GnomeModule(ExtensionModule):
         cflags = OrderedSet()
         ldflags = OrderedSet()
         gi_includes = OrderedSet()
-        deps = mesonlib.listify(deps)
+        deps = mesonlib.listify(deps, unholder=True)
 
         for dep in deps:
-            if hasattr(dep, 'held_object'):
-                dep = dep.held_object
             if isinstance(dep, InternalDependency):
                 cflags.update(get_include_args(dep.include_directories))
                 for lib in dep.libraries:
@@ -378,7 +376,7 @@ class GnomeModule(ExtensionModule):
             elif isinstance(dep, (build.StaticLibrary, build.SharedLibrary)):
                 cflags.update(get_include_args(dep.get_include_dirs()))
             else:
-                mlog.log('dependency %s not handled to build gir files' % dep)
+                mlog.log('dependency {!r} not handled to build gir files'.format(dep))
                 continue
 
         if gir_has_extra_lib_arg() and use_gir_args:
@@ -417,7 +415,7 @@ class GnomeModule(ExtensionModule):
             raise MesonException('gobject-introspection dependency was not found, gir cannot be generated.')
         ns = kwargs.pop('namespace')
         nsversion = kwargs.pop('nsversion')
-        libsources = mesonlib.flatten(kwargs.pop('sources'))
+        libsources = mesonlib.extract_as_list(kwargs, 'sources', pop=True)
         girfile = '%s-%s.gir' % (ns, nsversion)
         srcdir = os.path.join(state.environment.get_source_dir(), state.subdir)
         builddir = os.path.join(state.environment.get_build_dir(), state.subdir)
@@ -531,9 +529,8 @@ class GnomeModule(ExtensionModule):
             else:
                 raise MesonException('Gir export packages must be str or list')
 
-        deps = mesonlib.extract_as_list(kwargs, 'dependencies', pop = True)
         deps = (girtarget.get_all_link_deps() + girtarget.get_external_deps() +
-                deps)
+                extract_as_list(kwargs, 'dependencies', pop=True, unholder=True))
         # Need to recursively add deps on GirTarget sources from our
         # dependencies and also find the include directories needed for the
         # typelib generation custom target below.
@@ -800,7 +797,8 @@ This will become a hard error in the future.''')
 
     def _get_build_args(self, kwargs, state):
         args = []
-        cflags, ldflags, gi_includes = self._get_dependencies_flags(kwargs.get('dependencies', []), state, include_rpath=True)
+        deps = extract_as_list(kwargs, 'dependencies', unholder=True)
+        cflags, ldflags, gi_includes = self._get_dependencies_flags(deps, state, include_rpath=True)
         inc_dirs = mesonlib.extract_as_list(kwargs, 'include_directories')
         for incd in inc_dirs:
             if not isinstance(incd.held_object, (str, build.IncludeDirs)):
diff --git a/run_unittests.py b/run_unittests.py
index b21771446..7ae994726 100755
--- a/run_unittests.py
+++ b/run_unittests.py
@@ -31,6 +31,7 @@ import mesonbuild.compilers
 import mesonbuild.environment
 import mesonbuild.mesonlib
 import mesonbuild.coredata
+from mesonbuild.interpreter import ObjectHolder
 from mesonbuild.mesonlib import is_linux, is_windows, is_osx, is_cygwin, windows_proof_rmtree
 from mesonbuild.environment import Environment
 from mesonbuild.dependencies import DependencyException
@@ -62,7 +63,6 @@ def get_soname(fname):
 def get_rpath(fname):
     return get_dynamic_section_entry(fname, r'(?:rpath|runpath)')
 
-
 class InternalTests(unittest.TestCase):
 
     def test_version_number(self):
@@ -398,6 +398,49 @@ class InternalTests(unittest.TestCase):
 
         self.assertEqual(forced_value, desired_value)
 
+    def test_listify(self):
+        listify = mesonbuild.mesonlib.listify
+        # Test sanity
+        self.assertEqual([1], listify(1))
+        self.assertEqual([], listify([]))
+        self.assertEqual([1], listify([1]))
+        # Test flattening
+        self.assertEqual([1, 2, 3], listify([1, [2, 3]]))
+        self.assertEqual([1, 2, 3], listify([1, [2, [3]]]))
+        self.assertEqual([1, [2, [3]]], listify([1, [2, [3]]], flatten=False))
+        # Test flattening and unholdering
+        holder1 = ObjectHolder(1)
+        holder3 = ObjectHolder(3)
+        self.assertEqual([holder1], listify(holder1))
+        self.assertEqual([holder1], listify([holder1]))
+        self.assertEqual([holder1, 2], listify([holder1, 2]))
+        self.assertEqual([holder1, 2, 3], listify([holder1, 2, [3]]))
+        self.assertEqual([1], listify(holder1, unholder=True))
+        self.assertEqual([1], listify([holder1], unholder=True))
+        self.assertEqual([1, 2], listify([holder1, 2], unholder=True))
+        self.assertEqual([1, 2, 3], listify([holder1, 2, [holder3]], unholder=True))
+        # Unholding doesn't work recursively when not flattening
+        self.assertEqual([1, [2], [holder3]], listify([holder1, [2], [holder3]], unholder=True, flatten=False))
+
+    def test_extract_as_list(self):
+        extract = mesonbuild.mesonlib.extract_as_list
+        # Test sanity
+        kwargs = {'sources': [1, 2, 3]}
+        self.assertEqual([1, 2, 3], extract(kwargs, 'sources'))
+        self.assertEqual(kwargs, {'sources': [1, 2, 3]})
+        self.assertEqual([1, 2, 3], extract(kwargs, 'sources', pop=True))
+        self.assertEqual(kwargs, {})
+        # Test unholding
+        holder3 = ObjectHolder(3)
+        kwargs = {'sources': [1, 2, holder3]}
+        self.assertEqual([1, 2, 3], extract(kwargs, 'sources', unholder=True))
+        self.assertEqual(kwargs, {'sources': [1, 2, holder3]})
+        self.assertEqual([1, 2, 3], extract(kwargs, 'sources', unholder=True, pop=True))
+        self.assertEqual(kwargs, {})
+        # Test listification
+        kwargs = {'sources': [1, 2, 3], 'pch_sources': [4, 5, 6]}
+        self.assertEqual([[1, 2, 3], [4, 5, 6]], extract(kwargs, 'sources', 'pch_sources'))
+
 
 class BasePlatformTests(unittest.TestCase):
     def setUp(self):
diff --git a/test cases/frameworks/7 gnome/gir/meson.build b/test cases/frameworks/7 gnome/gir/meson.build
index 3598b663d..a91cb977a 100644
--- a/test cases/frameworks/7 gnome/gir/meson.build	
+++ b/test cases/frameworks/7 gnome/gir/meson.build	
@@ -27,7 +27,7 @@ gnome.generate_gir(
   identifier_prefix : 'Meson',
   includes : ['GObject-2.0', 'MesonDep1-1.0'],
   # dep1_dep pulls in dep2_dep for us
-  dependencies : [fake_dep, dep1_dep],
+  dependencies : [[fake_dep, dep1_dep]],
   install : true,
   build_by_default : true,
   # Test that unknown kwargs do not crash the parser.