1 files changed, 1 insertions, 0 deletions
diff --git a/utf8.c b/utf8.c
index 3c80bd2197..b44057c40d 100644
--- a/utf8.c
+++ b/utf8.c
@@ -1726,6 +1726,7 @@ Perl_swash_fetch(pTHX_ SV *swash, const U8 *ptr, bool do_utf8)
 	}
 
 	PL_last_swash_hv = hv;
+	assert(klen <= sizeof(PL_last_swash_key));
 	PL_last_swash_klen = (U8)klen;
 	/* FIXME change interpvar.h?  */
 	PL_last_swash_tmps = (U8 *) tmps;