diff --git a/src/cpBody.c b/src/cpBody.c
index 8ad2bc99..4ba4b494 100644
--- a/src/cpBody.c
+++ b/src/cpBody.c
@@ -103,9 +103,9 @@ cpBodyFree(cpBody *body)
 #ifdef NDEBUG
 	#define	cpAssertSaneBody(body)
 #else
-	static void cpv_assert_nan(cpVect v, char *message){cpAssertHard(v.x == v.x && v.y == v.y, message);}
-	static void cpv_assert_infinite(cpVect v, char *message){cpAssertHard(cpfabs(v.x) != INFINITY && cpfabs(v.y) != INFINITY, message);}
-	static void cpv_assert_sane(cpVect v, char *message){cpv_assert_nan(v, message); cpv_assert_infinite(v, message);}
+	static void cpv_assert_nan(cpVect v, const char *message){cpAssertHard(v.x == v.x && v.y == v.y, message);}
+	static void cpv_assert_infinite(cpVect v, const char *message){cpAssertHard(cpfabs(v.x) != INFINITY && cpfabs(v.y) != INFINITY, message);}
+	static void cpv_assert_sane(cpVect v, const char *message){cpv_assert_nan(v, message); cpv_assert_infinite(v, message);}
 	
 	static void
 	cpBodySanityCheck(const cpBody *body)