1 files changed, 3 insertions, 1 deletions
diff --git a/math.c b/math.c
index bf9b598156..9a6d459797 100644
--- a/math.c
+++ b/math.c
@@ -22,10 +22,12 @@ VALUE rb_mMath;
     Need_Float(y);\
 } while (0)
 
+static void domain_check _((double x, const char *msg));
+
 static void
 domain_check(x, msg)
     double x;
-    char *msg;
+    const char *msg;
 {
     while(1) {
 	if (errno) {