diff --git a/src/util/unicode.test.c b/src/util/unicode.test.c
index dc33b02a8..f485808cb 100644
--- a/src/util/unicode.test.c
+++ b/src/util/unicode.test.c
@@ -18,7 +18,8 @@ static void test_unicode_tolower(CuTest * tc)
 
 static void test_unicode_utf8_to_other(CuTest *tc)
 {
-    const char utf8_str[] = { 0xc3, 0x98, 0xc5, 0xb8, 0xc2, 0x9d, 'l', 0 }; // ØŸl
+    const unsigned char uchar_str[] = { 0xc3, 0x98, 0xc5, 0xb8, 0xc2, 0x9d, 'l', 0 }; // ØŸl
+    utf8_t *utf8_str = (utf8_t *)uchar_str;
     unsigned char ch;
     size_t sz;
     CuAssertIntEquals(tc, 0, unicode_utf8_to_cp437(&ch, utf8_str, &sz));