diff --git a/llvm/tools/llvm-c-test/llvm-c-test.h b/llvm/tools/llvm-c-test/llvm-c-test.h
index 0401f1d..2a70904 100644
--- a/llvm/tools/llvm-c-test/llvm-c-test.h
+++ b/llvm/tools/llvm-c-test/llvm-c-test.h
@@ -53,8 +53,8 @@
 int llvm_test_diagnostic_handler(void);
 
 // attributes.c
-int llvm_test_function_attributes();
-int llvm_test_callsite_attributes();
+int llvm_test_function_attributes(void);
+int llvm_test_callsite_attributes(void);
 
 #ifdef __cplusplus
 }