diff -up openssl-1.1.0-pre5/crypto/rsa/rsa_gen.c.cc-reqs openssl-1.1.0-pre5/crypto/rsa/rsa_gen.c
--- openssl-1.1.0-pre5/crypto/rsa/rsa_gen.c.cc-reqs	2016-04-19 16:57:54.000000000 +0200
+++ openssl-1.1.0-pre5/crypto/rsa/rsa_gen.c	2016-07-20 17:01:49.929695542 +0200
@@ -123,6 +123,12 @@ static int rsa_builtin_keygen(RSA *rsa,
     if (!rsa->iqmp && ((rsa->iqmp = BN_secure_new()) == NULL))
         goto err;
 
+    /* prepare minimum p and q difference */
+    if (!BN_one(r3))
+        goto err;
+    if (bitsp > 100 && !BN_lshift(r3, r3, bitsp - 100))
+        goto err;
+
     BN_copy(rsa->e, e_value);
 
     /* generate p and q */
@@ -150,7 +156,9 @@ static int rsa_builtin_keygen(RSA *rsa,
         do {
             if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL, cb))
                 goto err;
-        } while ((BN_cmp(rsa->p, rsa->q) == 0) && (++degenerate < 3));
+            if (!BN_sub(r2, rsa->q, rsa->p))
+                goto err;
+        } while ((BN_ucmp(r2, r3) <= 0) && (++degenerate < 3));
         if (degenerate == 3) {
             ok = 0;             /* we set our own err */
             RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_SIZE_TOO_SMALL);