diff --git a/g10/ChangeLog b/g10/ChangeLog
index 99a3d5ccd..a9786a26c 100644
--- a/g10/ChangeLog
+++ b/g10/ChangeLog
@@ -1,3 +1,8 @@
+2004-06-16  David Shaw  <dshaw@jabberwocky.com>
+
+	* keygen.c (make_backsig): Make sure that the backsig was built
+	successfully before we try and use it.
+
 2004-06-16  Werner Koch  <wk@gnupg.org>
 
 	* free-packet.c (copy_secret_key): Get last fix right.
diff --git a/g10/keygen.c b/g10/keygen.c
index ff415c981..6b1ff98a6 100644
--- a/g10/keygen.c
+++ b/g10/keygen.c
@@ -551,69 +551,73 @@ make_backsig(PKT_signature *sig, PKT_public_key *pk,
       /* get it into a binary packed form. */
       IOBUF backsig_out=iobuf_temp();
       PACKET backsig_pkt;
-      byte *buf;
-      size_t pktlen=0;
  
       init_packet(&backsig_pkt);
       backsig_pkt.pkttype=PKT_SIGNATURE;
       backsig_pkt.pkt.signature=backsig;
-      build_packet(backsig_out,&backsig_pkt);
+      rc=build_packet(backsig_out,&backsig_pkt);
       free_packet(&backsig_pkt);
-      buf=iobuf_get_temp_buffer(backsig_out);
- 
-      /* Remove the packet header */
-      if(buf[0]&0x40)
- 	{
- 	  if(buf[1]<192)
- 	    {
- 	      pktlen=buf[1];
- 	      buf+=2;
- 	    }
- 	  else if(buf[1]<224)
- 	    {
- 	      pktlen=(buf[1]-192)*256;
- 	      pktlen+=buf[2]+192;
- 	      buf+=3;
- 	    }
- 	  else if(buf[1]==255)
- 	    {
- 	      pktlen =buf[2] << 24;
- 	      pktlen|=buf[3] << 16;
- 	      pktlen|=buf[4] << 8;
- 	      pktlen|=buf[5];
- 	      buf+=6;
- 	    }
-	  else
-	    BUG();
- 	}
+      if(rc)
+	log_error("build_packet failed for backsig: %s\n",g10_errstr(rc));
       else
- 	{
- 	  int mark=1;
+	{
+	  size_t pktlen=0;
+	  byte *buf=iobuf_get_temp_buffer(backsig_out);
  
- 	  switch(buf[0]&3)
- 	    {
- 	    case 3:
- 	      BUG();
- 	      break;
+	  /* Remove the packet header */
+	  if(buf[0]&0x40)
+	    {
+	      if(buf[1]<192)
+		{
+		  pktlen=buf[1];
+		  buf+=2;
+		}
+	      else if(buf[1]<224)
+		{
+		  pktlen=(buf[1]-192)*256;
+		  pktlen+=buf[2]+192;
+		  buf+=3;
+		}
+	      else if(buf[1]==255)
+		{
+		  pktlen =buf[2] << 24;
+		  pktlen|=buf[3] << 16;
+		  pktlen|=buf[4] << 8;
+		  pktlen|=buf[5];
+		  buf+=6;
+		}
+	      else
+		BUG();
+	    }
+	  else
+	    {
+	      int mark=1;
  
- 	    case 2:
- 	      pktlen =buf[mark++] << 24;
- 	      pktlen|=buf[mark++] << 16;
+	      switch(buf[0]&3)
+		{
+		case 3:
+		  BUG();
+		  break;
  
- 	    case 1:
- 	      pktlen|=buf[mark++] << 8;
+		case 2:
+		  pktlen =buf[mark++] << 24;
+		  pktlen|=buf[mark++] << 16;
  
- 	    case 0:
- 	      pktlen|=buf[mark++];
- 	    }
+		case 1:
+		  pktlen|=buf[mark++] << 8;
  
- 	  buf+=mark;
- 	}
+		case 0:
+		  pktlen|=buf[mark++];
+		}
  
-      /* now make the binary blob into a subpacket */
-      build_sig_subpkt(sig,SIGSUBPKT_SIGNATURE,buf,pktlen);
+	      buf+=mark;
+	    }
+ 
+	  /* now make the binary blob into a subpacket */
+	  build_sig_subpkt(sig,SIGSUBPKT_SIGNATURE,buf,pktlen);
 
-      iobuf_close(backsig_out);
+	  iobuf_close(backsig_out);
+	}
     }
  
   return rc;