diff --git a/lib/isc/include/isc/util.h b/lib/isc/include/isc/util.h
index 805e518afc..9fed22df60 100644
--- a/lib/isc/include/isc/util.h
+++ b/lib/isc/include/isc/util.h
@@ -140,18 +140,7 @@
 #define ISC_NO_SANITIZE_THREAD
 #endif /* if __SANITIZE_THREAD__ */
 
-#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR >= 6)
 #define STATIC_ASSERT(cond, msg) _Static_assert(cond, msg)
-#elif __has_feature(c_static_assert)
-#define STATIC_ASSERT(cond, msg) _Static_assert(cond, msg)
-#else /* if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR >= 6) */
-
-/* Courtesy of Joseph Quinsey: https://godbolt.org/z/K9RvWS */
-#define TOKENPASTE(a, b)	a##b /* "##" is the "Token Pasting Operator" */
-#define EXPAND_THEN_PASTE(a, b) TOKENPASTE(a, b) /* expand then paste */
-#define STATIC_ASSERT(x, msg) \
-	enum { EXPAND_THEN_PASTE(ASSERT_line_, __LINE__) = 1 / ((msg) && (x)) }
-#endif /* if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR >= 6) */
 
 #ifdef UNIT_TESTING
 extern void