diff --git a/expat/tests/chardata.c b/expat/tests/chardata.c
index 02243e04..012499bb 100644
--- a/expat/tests/chardata.c
+++ b/expat/tests/chardata.c
@@ -47,7 +47,7 @@ CharData_AppendString(CharData *storage, const char *s)
     if ((len + storage->count) > maxchars) {
         len = (maxchars - storage->count);
     }
-    if (len + storage->count < sizeof(storage->data)) {
+    if (len + storage->count < (int)sizeof(storage->data)) {
         memcpy(storage->data + storage->count, s, len);
         storage->count += len;
     }
@@ -68,7 +68,7 @@ CharData_AppendXMLChars(CharData *storage, const XML_Char *s, int len)
     if ((len + storage->count) > maxchars) {
         len = (maxchars - storage->count);
     }
-    if (len + storage->count < sizeof(storage->data)) {
+    if (len + storage->count < (int)sizeof(storage->data)) {
         memcpy(storage->data + storage->count, s,
                len * sizeof(storage->data[0]));
         storage->count += len;