diff --git a/src/secp256k1/src/tests.c b/src/secp256k1/src/tests.c
--- a/src/secp256k1/src/tests.c
+++ b/src/secp256k1/src/tests.c
@@ -5187,7 +5187,7 @@
         const char* ch = argv[2];
         while (pos < 16 && ch[0] != 0 && ch[1] != 0) {
             unsigned short sh;
-            if (sscanf(ch, "%2hx", &sh)) {
+            if ((sscanf(ch, "%2hx", &sh)) == 1) {
                 seed16[pos] = sh;
             } else {
                 break;