diff --git a/compiler-rt/lib/builtins/CMakeLists.txt b/compiler-rt/lib/builtins/CMakeLists.txt
index 13adbd6c4d57d..2c3b0fa84a478 100644
--- a/compiler-rt/lib/builtins/CMakeLists.txt
+++ b/compiler-rt/lib/builtins/CMakeLists.txt
@@ -868,10 +868,12 @@ else ()
           endif()
         endif()
       endif()
-      check_c_source_compiles("_Float16 foo(_Float16 x) { return x; }"
+      check_c_source_compiles("_Float16 foo(_Float16 x) { return x; }
+                               int main(void) { return 0; }"
                               COMPILER_RT_HAS_${arch}_FLOAT16)
       append_list_if(COMPILER_RT_HAS_${arch}_FLOAT16 -DCOMPILER_RT_HAS_FLOAT16 BUILTIN_CFLAGS_${arch})
-      check_c_source_compiles("__bf16 foo(__bf16 x) { return x; }"
+      check_c_source_compiles("__bf16 foo(__bf16 x) { return x; }
+                               int main(void) { return 0; }"
                               COMPILER_RT_HAS_${arch}_BFLOAT16)
       # Build BF16 files only when "__bf16" is available.
       if(COMPILER_RT_HAS_${arch}_BFLOAT16)