diff --git a/lib/isc/include/isc/overflow.h b/lib/isc/include/isc/overflow.h
index 62727513ad..bd8e4eec73 100644
--- a/lib/isc/include/isc/overflow.h
+++ b/lib/isc/include/isc/overflow.h
@@ -39,29 +39,11 @@
  *	INSIST(!overflow);
  */
 
-#if HAVE_BUILTIN_MUL_OVERFLOW
 #define ISC_OVERFLOW_MUL(a, b, cp) __builtin_mul_overflow(a, b, cp)
-#else
-#define ISC_OVERFLOW_MUL(a, b, cp)                                           \
-	((ISC_OVERFLOW_UINT_MAX(a) / (b) > (a)) ? (*(cp) = (a) * (b), false) \
-						: true)
-#endif
 
-#if HAVE_BUILTIN_ADD_OVERFLOW
 #define ISC_OVERFLOW_ADD(a, b, cp) __builtin_add_overflow(a, b, cp)
-#else
-#define ISC_OVERFLOW_ADD(a, b, cp)                                           \
-	((ISC_OVERFLOW_UINT_MAX(a) - (b) > (a)) ? (*(cp) = (a) + (b), false) \
-						: true)
-#endif
 
-#if HAVE_BUILTIN_SUB_OVERFLOW
 #define ISC_OVERFLOW_SUB(a, b, cp) __builtin_sub_overflow(a, b, cp)
-#else
-#define ISC_OVERFLOW_SUB(a, b, cp)                                           \
-	((ISC_OVERFLOW_UINT_MIN(a) + (b) < (a)) ? (*(cp) = (a) - (b), false) \
-						: true)
-#endif
 
 #define ISC_CHECKED_MUL(a, b)                                      \
 	({                                                         \
diff --git a/meson.build b/meson.build
index d0ae062092..133e6d1e8f 100644
--- a/meson.build
+++ b/meson.build
@@ -316,12 +316,14 @@ endif
 
 foreach fn : [
     '__builtin_add_overflow',
+    '__builtin_expect',
     '__builtin_mul_overflow',
+    '__builtin_prefetch',
     '__builtin_sub_overflow',
     '__builtin_unreachable',
 ]
-    if cc.has_function(fn)
-        config.set('HAVE_@0@'.format(fn.substring(2).to_upper()), 1)
+    if not cc.has_function(fn)
+        error('@0@ support required'.format(fn))
     endif
 endforeach