diff --git a/tests/unit-tests/test_ecc.c b/tests/unit-tests/test_ecc.c
index a2dc99fe..4969d56b 100644
--- a/tests/unit-tests/test_ecc.c
+++ b/tests/unit-tests/test_ecc.c
@@ -129,7 +129,7 @@ t_test_ecc_dh(void) {
   uint32_t tempBy2[8];
   uint32_t secretA[8];
   uint32_t secretB[8];
-  int ret;
+  size_t ret;
 
   ret = dtls_prng((void *)secretA, sizeof(secretA));
   CU_ASSERT(ret > 1);