diff --git a/mesonbuild/compilers/c.py b/mesonbuild/compilers/c.py
index 3b58a07..9ef9207 100644
--- a/mesonbuild/compilers/c.py
+++ b/mesonbuild/compilers/c.py
@@ -70,6 +70,7 @@ 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/clike.py b/mesonbuild/compilers/clike.py
index e923ff2..7ba8bd3 100644
--- a/mesonbuild/compilers/clike.py
+++ b/mesonbuild/compilers/clike.py
@@ -375,6 +375,7 @@ class CLikeCompiler:
             #ifndef {symbol}
                 {symbol};
             #endif
+            return 0;
         }}'''
         return self.compiles(t.format(**fargs), env, extra_args=extra_args,
                              dependencies=dependencies)
@@ -583,6 +584,7 @@ class CLikeCompiler:
         {prefix}
         int main(int argc, char **argv) {{
             {type} something;
+            return 0;
         }}'''
         if not self.compiles(t.format(**fargs), env, extra_args=extra_args,
                              dependencies=dependencies)[0]:
@@ -661,6 +663,7 @@ class CLikeCompiler:
         #include <stdio.h>
         int main(int argc, char *argv[]) {{
             printf ("{fmt}", {cast} {f}());
+            return 0;
         }}'''.format(**fargs)
         res = self.run(code, env, extra_args=extra_args, dependencies=dependencies)
         if not res.compiled:
@@ -813,6 +816,7 @@ 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)