diff --git a/library/rsa.c b/library/rsa.c
index f44b2c3..01d0eb0 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -1351,7 +1351,8 @@
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     size_t ilen, i, pad_len;
-    unsigned char *p, bad, pad_done;
+    unsigned char *p, pad_done;
+    int bad;
     unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
     unsigned char lhash[MBEDTLS_MD_MAX_SIZE];
     unsigned int hlen;
@@ -1439,9 +1440,8 @@
     p += hlen; /* Skip seed */
 
     /* Check lHash */
-    for (i = 0; i < hlen; i++) {
-        bad |= lhash[i] ^ *p++;
-    }
+    bad |= mbedtls_ct_memcmp(lhash, p, hlen);
+    p += hlen;
 
     /* Get zero-padding len, but always read till end of buffer
      * (minus one, for the 01 byte) */