diff --git a/src/misc/compare_testvector.c b/src/misc/compare_testvector.c
index 874794ff..fd8ae0c7 100644
--- a/src/misc/compare_testvector.c
+++ b/src/misc/compare_testvector.c
@@ -59,7 +59,7 @@ int ltc_compare_testvector(const void* is, const unsigned long is_len, const voi
    int res = 0;
    if(is_len != should_len) {
       res = is_len > should_len ? -1 : 1;
-   } else if (is_len == 0) {
+   } else if (is_len == 0 && (!is || !should)) {
       res = 0;
    } else {
       res = XMEMCMP(is, should, is_len);