diff --git a/string.c b/string.c
index 9902b0feb3..82fa603ada 100644
--- a/string.c
+++ b/string.c
@@ -483,7 +483,7 @@ search_nonascii(const char *p, const char *e)
 #endif
 #ifdef HAVE_BUILTIN___BUILTIN_ASSUME_ALIGNED
 #define aligned_ptr(value) \
-        __builtin_assume_aligned((value), sizeof(uintptr_t *))
+        __builtin_assume_aligned((value), sizeof(uintptr_t))
 #else
 #define aligned_ptr(value) (uintptr_t *)(value)
 #endif