--- comcom.c.old	Sat Jan 11 05:44:58 2003
+++ comcom.c	Sun Jan 12 20:07:03 2003
@@ -3514,15 +3514,20 @@
 static int duplicate_env(int size)
 {
 	struct com_starter_seg  *ctcb = CTCB;
-	struct com_MCB *mcb = (void *)((ctcb->envir_frame-1) << 4);
 	char *newenv;
-	int oldsize = mcb->size << 4;
+	struct com_MCB *mcb = NULL;
+	int oldsize = 0;
 
+	if (ctcb->envir_frame) {
+	    mcb = (void *)((ctcb->envir_frame-1) << 4);
+	    oldsize = mcb->size << 4;
+	}
 	size = (size+15) & -16;
 	if (size <= oldsize) size = oldsize;
 	newenv = (char *)com_dosallocmem(size);
 	if ((int)newenv < 0) return oldsize;	/* giving up */
-	memcpy(newenv, ((char *)mcb)+16, oldsize);
+	if (oldsize)
+	    memcpy(newenv, ((char *)mcb)+16, oldsize);
 	ctcb->envir_frame = ((unsigned int)newenv) >> 4;
 	return size;
 }