diff --git a/src/regexp_nfa.c b/src/regexp_nfa.c
index cba4001..8146d9d 100644
--- a/src/regexp_nfa.c
+++ b/src/regexp_nfa.c
@@ -3642,14 +3642,14 @@
 	    if (i < sub1->in_use)
 		s1 = sub1->list.multi[i].start.lnum;
 	    else
-		s1 = 0;
+		s1 = -1;
 	    if (i < sub2->in_use)
 		s2 = sub2->list.multi[i].start.lnum;
 	    else
-		s2 = 0;
+		s2 = -1;
 	    if (s1 != s2)
 		return FALSE;
-	    if (s1 != 0 && sub1->list.multi[i].start.col
+	    if (s1 != -1 && sub1->list.multi[i].start.col
 					     != sub2->list.multi[i].start.col)
 		return FALSE;
 	}
@@ -3931,8 +3931,9 @@
 	    if (state->lastlist[nfa_ll_index] == l->id)
 	    {
 		/* This state is already in the list, don't add it again,
-		 * unless it is an MOPEN that is used for a backreference. */
-		if (!nfa_has_backref)
+		 * unless it is an MOPEN that is used for a backreference or
+		 * when there is a PIM. */
+		if (!nfa_has_backref && pim == NULL)
 		{
 skip_add:
 #ifdef ENABLE_LOG
@@ -3949,9 +3950,9 @@
 		    goto skip_add;
 	    }
 
-	    /* When there are backreferences the number of states may be (a
-	     * lot) bigger than anticipated. */
-	    if (nfa_has_backref && l->n == l->len)
+	    /* When there are backreferences or PIMs the number of states may
+	     * be (a lot) bigger than anticipated. */
+	    if (l->n == l->len)
 	    {
 		int newlen = l->len * 3 / 2 + 50;
 
diff --git a/src/testdir/test64.in b/src/testdir/test64.in
index 4fdbcf7..a7b5794 100644
--- a/src/testdir/test64.in
+++ b/src/testdir/test64.in
@@ -338,6 +338,7 @@
 :call add(tl, [2, '^\%(.*bar\)\@!.*\zsfoo', ' bar foo '])
 :call add(tl, [2, '^\%(.*bar\)\@!.*\zsfoo', ' foo bar '])
 :call add(tl, [2, '^\%(.*bar\)\@!.*\zsfoo', ' foo xxx ', 'foo'])
+:call add(tl, [2, '[ ]\@!\p\%([ ]\@!\p\)*:', 'implicit mappings:', 'mappings:'])
 :"
 :"""" Combining different tests and features
 :call add(tl, [2, '[[:alpha:]]\{-2,6}', '787abcdiuhsasiuhb4', 'ab'])
diff --git a/src/testdir/test64.ok b/src/testdir/test64.ok
index d1f4113..8aa5a60 100644
--- a/src/testdir/test64.ok
+++ b/src/testdir/test64.ok
@@ -770,6 +770,9 @@
 OK 0 - ^\%(.*bar\)\@!.*\zsfoo
 OK 1 - ^\%(.*bar\)\@!.*\zsfoo
 OK 2 - ^\%(.*bar\)\@!.*\zsfoo
+OK 0 - [ ]\@!\p\%([ ]\@!\p\)*:
+OK 1 - [ ]\@!\p\%([ ]\@!\p\)*:
+OK 2 - [ ]\@!\p\%([ ]\@!\p\)*:
 OK 0 - [[:alpha:]]\{-2,6}
 OK 1 - [[:alpha:]]\{-2,6}
 OK 2 - [[:alpha:]]\{-2,6}
diff --git a/src/version.c b/src/version.c
index fb70ebc..025b856 100644
--- a/src/version.c
+++ b/src/version.c
@@ -729,6 +729,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1247,
+/**/
     1246,
 /**/
     1245,