diff --git a/library/ecp.c b/library/ecp.c
index b0ef3ca..a58e8a6 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -2803,7 +2803,7 @@
     {
         /* SEC1 3.2.1: Generate d such that 1 <= n < N */
         int count = 0;
-        int cmp = 0;
+        unsigned cmp = 0;
 
         /*
          * Match the procedure given in RFC 6979 (deterministic ECDSA):
@@ -2829,13 +2829,13 @@
             if( ++count > 30 )
                 return( MBEDTLS_ERR_ECP_RANDOM_FAILED );
 
-            ret = mbedtls_mpi_cmp_mpi_ct( d, &grp->N, &cmp );
+            ret = mbedtls_mpi_lt_mpi_ct( d, &grp->N, &cmp );
             if( ret != 0 )
             {
                 goto cleanup;
             }
         }
-        while( mbedtls_mpi_cmp_int( d, 1 ) < 0 || cmp >= 0 );
+        while( mbedtls_mpi_cmp_int( d, 1 ) < 0 || cmp != 1 );
     }
 #endif /* ECP_SHORTWEIERSTRASS */