diff --git a/ext/refinement/refinement.c b/ext/refinement/refinement.c
index 43ec2fb8b0..44ffd2a0b8 100644
--- a/ext/refinement/refinement.c
+++ b/ext/refinement/refinement.c
@@ -1,4 +1,11 @@
 void ruby_Init_refinement(void);
+#ifdef __GNUC__
+#define PRINTF_ARGS(decl, string_index, first_to_check) \
+  decl __attribute__((format(printf, string_index, first_to_check)))
+#else
+#define PRINTF_ARGS(decl, string_index, first_to_check) decl
+#endif
+PRINTF_ARGS(void rb_warn(const char*, ...), 1, 2);
 
 void
 Init_refinement(void)