diff --git a/testsuite/c_test/sanity_test/SANITY0027-convert/convert.c b/testsuite/c_test/sanity_test/SANITY0027-convert/convert.c
index f86b630dfd1a7c9ca9ceb4ff93e499f09699d883..848ecbbe99809ca706089b6090e9b180f56a6c1a 100644
--- a/testsuite/c_test/sanity_test/SANITY0027-convert/convert.c
+++ b/testsuite/c_test/sanity_test/SANITY0027-convert/convert.c
@@ -16,7 +16,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-char c = 0xff;
+signed char c = 0xff;
 unsigned char uc = 0xff;
 short s;
 int i;