diff --git a/mesonbuild/compilers.py b/mesonbuild/compilers.py
index 4088adc1c955..5d3dc99cba6f 100644
--- a/mesonbuild/compilers.py
+++ b/mesonbuild/compilers.py
@@ -2126,6 +2126,9 @@ def get_option_compile_args(self, options):
     def get_option_link_args(self, options):
         return []
 
+    def has_argument(self, arg, env):
+        return super().has_argument(['-Werror=unknown-warning-option', arg], env)
+
 class GnuCPPCompiler(CPPCompiler):
     # may need to separate the latter to extra_debug_args or something
     std_debug_args = ['-g']
@@ -2240,6 +2243,9 @@ def get_option_compile_args(self, options):
     def get_option_link_args(self, options):
         return []
 
+    def has_argument(self, arg, env):
+        return super().has_argument(['-Werror=unknown-warning-option', arg], env)
+
 class FortranCompiler(Compiler):
     def __init__(self, exelist, version, is_cross, exe_wrapper=None):
         super().__init__(exelist, version)
diff --git a/test cases/common/103 manygen/subdir/manygen.py b/test cases/common/103 manygen/subdir/manygen.py
index c233ae6bc0a4..4fd2f252eac2 100755
--- a/test cases/common/103 manygen/subdir/manygen.py	
+++ b/test cases/common/103 manygen/subdir/manygen.py	
@@ -22,7 +22,8 @@
         shutil.which('clang') or \
         shutil.which('cc')
 
-if 'cl' in os.path.basename(compiler):
+compbase = os.path.basename(compiler)
+if 'cl' in compbase and 'clang' not in compbase:
     libsuffix = '.lib'
     is_vs = True
     compiler = 'cl'