diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index 56c786b5a..26cba40bf 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -618,7 +618,7 @@ class Backend():
                 dfilename = os.path.join(outdir, target.depfile)
                 i = i.replace('@DEPFILE@', dfilename)
             elif '@PRIVATE_OUTDIR_' in i:
-                match = re.search('@PRIVATE_OUTDIR_(ABS_)?([^\/\s*]*)@', i)
+                match = re.search('@PRIVATE_OUTDIR_(ABS_)?([^/\s*]*)@', i)
                 if not match:
                     msg = 'Custom target {!r} has an invalid argument {!r}' \
                           ''.format(target.name, i)
diff --git a/mesonbuild/mparser.py b/mesonbuild/mparser.py
index fa8ade2cc..a0053170a 100644
--- a/mesonbuild/mparser.py
+++ b/mesonbuild/mparser.py
@@ -47,7 +47,7 @@ class Lexer:
             ('eol_cont', re.compile(r'\\\n')),
             ('eol', re.compile(r'\n')),
             ('multiline_string', re.compile(r"'''(.|\n)*?'''", re.M)),
-            ('comment', re.compile(r'\#.*')),
+            ('comment', re.compile(r'#.*')),
             ('lparen', re.compile(r'\(')),
             ('rparen', re.compile(r'\)')),
             ('lbracket', re.compile(r'\[')),
@@ -60,11 +60,11 @@ class Lexer:
             ('plus', re.compile(r'\+')),
             ('dash', re.compile(r'-')),
             ('star', re.compile(r'\*')),
-            ('percent', re.compile(r'\%')),
+            ('percent', re.compile(r'%')),
             ('fslash', re.compile(r'/')),
             ('colon', re.compile(r':')),
             ('equal', re.compile(r'==')),
-            ('nequal', re.compile(r'\!=')),
+            ('nequal', re.compile(r'!=')),
             ('assign', re.compile(r'=')),
             ('le', re.compile(r'<=')),
             ('lt', re.compile(r'<')),
diff --git a/tools/cmake2meson.py b/tools/cmake2meson.py
index 647d0c30d..9f2c7c00f 100755
--- a/tools/cmake2meson.py
+++ b/tools/cmake2meson.py
@@ -38,7 +38,7 @@ class Lexer:
             ('varexp', re.compile(r'\${[-_0-9a-z/A-Z.]+}')),
             ('id', re.compile('''[,-><${}=+_0-9a-z/A-Z|@.*]+''')),
             ('eol', re.compile(r'\n')),
-            ('comment', re.compile(r'\#.*')),
+            ('comment', re.compile(r'#.*')),
             ('lparen', re.compile(r'\(')),
             ('rparen', re.compile(r'\)')),
         ]