diff --git a/coredata.py b/coredata.py
index a24f594e1..ea02b39b5 100644
--- a/coredata.py
+++ b/coredata.py
@@ -34,6 +34,13 @@ class CoreData():
         self.strip = options.strip
         self.coverage = options.coverage
 
+        if isinstance(options, CoreData):
+            self.compilers = options.compilers.copy()
+            self.deps = options.deps.copy()
+        else:
+            self.compilers = {}
+            self.deps = {}
+
 def load(filename):
     obj = pickle.load(open(filename, 'rb'))
     if not isinstance(obj, CoreData):
diff --git a/environment.py b/environment.py
index 84d08ae4c..cf7158e17 100755
--- a/environment.py
+++ b/environment.py
@@ -264,6 +264,12 @@ class Environment():
     def get_script_dir(self):
         return os.path.dirname(self.meson_script_file)
 
+    def get_old_coredata(self):
+        return self.old_coredata
+
+    def get_new_coredata(self):
+        return self.new_coredata
+
     def get_build_command(self):
         return self.meson_script_file
 
@@ -397,6 +403,9 @@ class Dependency():
     def get_link_flags(self):
         return []
 
+    def found(self):
+        return False
+
 # This should be an InterpreterObject. Fix it.
 
 class PkgConfigDependency(Dependency):
@@ -404,6 +413,7 @@ class PkgConfigDependency(Dependency):
     
     def __init__(self, name):
         Dependency.__init__(self)
+        self.is_found = False
         if not PkgConfigDependency.pkgconfig_found:
             self.check_pkgconfig()
 
@@ -411,22 +421,27 @@ class PkgConfigDependency(Dependency):
                                  stderr=subprocess.PIPE)
         out = p.communicate()[0]
         if p.returncode != 0:
-            raise RuntimeError('Dependency %s not known to pkg-config.' % name)
-        self.modversion = out.decode().strip()
-        p = subprocess.Popen(['pkg-config', '--cflags', name], stdout=subprocess.PIPE,
+            print('Dependency %s not known to pkg-config.' % name)
+            self.modversion = 'none'
+            self.cflags = []
+            self.libs = []
+        else:
+            self.is_found = True
+            self.modversion = out.decode().strip()
+            p = subprocess.Popen(['pkg-config', '--cflags', name], stdout=subprocess.PIPE,
                                  stderr=subprocess.PIPE)
-        out = p.communicate()[0]
-        if p.returncode != 0:
-            raise RuntimeError('Could not generate cflags for %s.' % name)
-        self.cflags = out.decode().split()
-        
-        p = subprocess.Popen(['pkg-config', '--libs', name], stdout=subprocess.PIPE,
+            out = p.communicate()[0]
+            if p.returncode != 0:
+                raise RuntimeError('Could not generate cflags for %s.' % name)
+            self.cflags = out.decode().split()
+
+            p = subprocess.Popen(['pkg-config', '--libs', name], stdout=subprocess.PIPE,
                                  stderr=subprocess.PIPE)
-        out = p.communicate()[0]
-        if p.returncode != 0:
-            raise RuntimeError('Could not generate libs for %s.' % name)
-        self.libs = out.decode().split()
-    
+            out = p.communicate()[0]
+            if p.returncode != 0:
+                raise RuntimeError('Could not generate libs for %s.' % name)
+            self.libs = out.decode().split()
+
     def get_modversion(self):
         return self.modversion
 
@@ -445,6 +460,9 @@ class PkgConfigDependency(Dependency):
         print('Found pkg-config version %s.' % out.decode().strip())
         PkgConfigDependency.pkgconfig_found = True
 
+    def found(self):
+        return self.is_found
+
 # Fixme, move to environment.
 def find_external_dependency(name, kwargs):
     # Add detectors for non-pkg-config deps (e.g. Boost) etc here.
diff --git a/interpreter.py b/interpreter.py
index 35c9a620b..3cdf8c49a 100755
--- a/interpreter.py
+++ b/interpreter.py
@@ -446,6 +446,8 @@ class Interpreter():
         self.build_def_files = [environment.build_filename]
         self.subdir = ''
         self.generators = []
+        self.old_coredata = self.environment.get_old_coredata()
+        self.new_coredata = self.environment.get_new_coredata()
 
     def build_func_dict(self):
         self.funcs = {'project' : self.func_project, 
@@ -464,7 +466,7 @@ class Interpreter():
                       'include_directories' : self.func_include_directories,
                       'add_global_arguments' : self.func_add_global_arguments,
                       }
-        
+
     def get_build_def_files(self):
         return self.build_def_files
 
@@ -563,19 +565,30 @@ class Interpreter():
 
     def add_languages(self, node, args):
         for lang in args:
-            if lang.lower() == 'c':
-                comp = self.environment.detect_c_compiler()
-            elif lang.lower() == 'cxx':
-                comp = self.environment.detect_cxx_compiler()
+            if lang in self.new_coredata.compilers:
+                comp = self.new_coredata.compilers[lang]
             else:
-                raise InvalidCode('Tried to use unknown language "%s".' % lang)
-            comp.sanity_check(self.environment.get_scratch_dir())
+                if lang.lower() == 'c':
+                    comp = self.environment.detect_c_compiler()
+                elif lang.lower() == 'cxx':
+                    comp = self.environment.detect_cxx_compiler()
+                else:
+                    raise InvalidCode('Tried to use unknown language "%s".' % lang)
+                comp.sanity_check(self.environment.get_scratch_dir())
+                self.new_coredata.compilers[lang] = comp
             self.build.compilers.append(comp)
 
     def func_find_dep(self, node, args, kwargs):
         self.validate_arguments(args, 1, [str])
         name = args[0]
-        dep = environment.find_external_dependency(name, kwargs)
+        if name in self.old_coredata.deps:
+            dep = self.old_coredata.deps[name]
+            if not dep.found():
+                raise RuntimeError('Non-found dependency stored in coredata.')
+        else:
+            dep = environment.find_external_dependency(name, kwargs)
+        if dep.found():
+            self.new_coredata.deps[name] = dep
         return dep
 
     def func_executable(self, node, args, kwargs):