diff --git a/g10/build-packet.c b/g10/build-packet.c
index 1353a863c..2745734b4 100644
--- a/g10/build-packet.c
+++ b/g10/build-packet.c
@@ -301,6 +301,8 @@ write_fake_data (IOBUF out, gcry_mpi_t a)
 
   if (!a)
     return 0;
+  if (!gcry_mpi_get_flag (a, GCRYMPI_FLAG_OPAQUE))
+    return 0; /* e.g. due to generating a key with wrong usage.  */
   p = gcry_mpi_get_opaque ( a, &n);
   if (!p)
     return 0; /* For example due to a read error in
diff --git a/g10/seskey.c b/g10/seskey.c
index c41a1455b..e5385af98 100644
--- a/g10/seskey.c
+++ b/g10/seskey.c
@@ -211,9 +211,12 @@ do_encode_md( gcry_md_hd_t md, int algo, size_t len, unsigned nbits,
     int i,n;
     gcry_mpi_t a;
 
-    if( len + asnlen + 4  > nframe )
-      log_bug ("can't encode a %d bit MD into a %d bits frame, algo=%d\n",
-               (int)(len*8), (int)nbits, algo);
+    if (len + asnlen + 4  > nframe)
+      {
+        log_error ("can't encode a %d bit MD into a %d bits frame, algo=%d\n",
+                   (int)(len*8), (int)nbits, algo);
+        return NULL;
+      }
 
     /* We encode the MD in this way:
      *