diff --git a/tests/tests-c-compiler/check-src/check-131.-gen-PER.c b/tests/tests-c-compiler/check-src/check-131.-gen-PER.c
index 7cc744f..ed29315 100644
--- a/tests/tests-c-compiler/check-src/check-131.-gen-PER.c
+++ b/tests/tests-c-compiler/check-src/check-131.-gen-PER.c
@@ -25,7 +25,7 @@
 
 	printf("Checking uper_open_type_put():\n");
 	assert(0 == uper_open_type_put(&asn_DEF_T, 0, &t, &po));
-	assert(po.nbits == (-1 + sizeof(po.tmpspace)) * 8);
+	assert(po.nbits == (-1 + (int)sizeof(po.tmpspace)) * 8);
 	printf("po{nboff=%zd; nbits=%zd; buffer=%p; tmpspace=%p}\n",
 		po.nboff, po.nbits, po.buffer, po.tmpspace);
 	/* One byte length and one byte 0x00 */