diff --git a/mesonbuild/compilers/c.py b/mesonbuild/compilers/c.py
index 47cfd981d..eff716106 100644
--- a/mesonbuild/compilers/c.py
+++ b/mesonbuild/compilers/c.py
@@ -67,6 +67,7 @@ class CCompiler(CLikeCompiler, Compiler):
             #ifndef {symbol}
                 {symbol};
             #endif
+            return 0;
         }}'''
         return self.compiles(t.format(**fargs), env, extra_args=extra_args,
                              dependencies=dependencies)
diff --git a/mesonbuild/compilers/mixins/clike.py b/mesonbuild/compilers/mixins/clike.py
index e032402ff..0591b7f12 100644
--- a/mesonbuild/compilers/mixins/clike.py
+++ b/mesonbuild/compilers/mixins/clike.py
@@ -332,6 +332,7 @@ class CLikeCompiler:
             #ifndef {symbol}
                 {symbol};
             #endif
+            return 0;
         }}'''
         return self.compiles(t.format(**fargs), env, extra_args=extra_args,
                              dependencies=dependencies)
@@ -555,6 +556,7 @@ class CLikeCompiler:
         {prefix}
         int main() {{
             {type} something;
+            return 0;
         }}'''
         if not self.compiles(t.format(**fargs), env, extra_args=extra_args,
                              dependencies=dependencies)[0]:
@@ -633,6 +635,7 @@ class CLikeCompiler:
         #include <stdio.h>
         int main() {{
             printf ("{fmt}", {cast} {f}());
+            return 0;
         }}'''.format(**fargs)
         res = self.run(code, env, extra_args=extra_args, dependencies=dependencies)
         if not res.compiled:
@@ -785,6 +788,7 @@ class CLikeCompiler:
                 #error "No definition for __builtin_{func} found in the prefix"
             #endif
         #endif
+        return 0;
         }}'''
         return self.links(t.format(**fargs), env, extra_args=extra_args,
                           dependencies=dependencies)