1 files changed, 0 insertions, 5 deletions
diff --git a/math.c b/math.c
index dd98d8806e..429826763d 100644
--- a/math.c
+++ b/math.c
@@ -26,11 +26,6 @@
 #include "internal/object.h"
 #include "internal/vm.h"
 
-#if defined(HAVE_SIGNBIT) && defined(__GNUC__) && defined(__sun) && \
-    !defined(signbit)
-    extern int signbit(double);
-#endif
-
 #define RB_BIGNUM_TYPE_P(x) RB_TYPE_P((x), T_BIGNUM)
 
 VALUE rb_mMath;