diff --git a/c_src/double-conversion/utils.h b/c_src/double-conversion/utils.h
index 7fb7f04..9ebb9ee 100644
--- a/c_src/double-conversion/utils.h
+++ b/c_src/double-conversion/utils.h
@@ -299,7 +299,7 @@ class StringBuilder {
 // PJD: 4-24-2013
 //
 
-#if defined(__GCC__)
+#if defined(__GNUC__)
 #define UNUSED __attribute__((unused))
 #else
 #define UNUSED