diff --git a/src/getchar.c b/src/getchar.c
index 29323fa..96e180f 100644
--- a/src/getchar.c
+++ b/src/getchar.c
@@ -446,9 +446,18 @@
 
     if (flush_typeahead == FLUSH_MINIMAL)
     {
-	// remove mapped characters at the start only
-	typebuf.tb_off += typebuf.tb_maplen;
-	typebuf.tb_len -= typebuf.tb_maplen;
+	// remove mapped characters at the start only,
+	// but only when enough space left in typebuf
+	if (typebuf.tb_off + typebuf.tb_maplen >= typebuf.tb_buflen)
+	{
+	    typebuf.tb_off = MAXMAPLEN;
+	    typebuf.tb_len = 0;
+	}
+	else
+	{
+	    typebuf.tb_off += typebuf.tb_maplen;
+	    typebuf.tb_len -= typebuf.tb_maplen;
+	}
 #if defined(FEAT_CLIENTSERVER) || defined(FEAT_EVAL)
 	if (typebuf.tb_len == 0)
 	    typebuf_was_filled = FALSE;
diff --git a/src/testdir/crash/heap_overflow3 b/src/testdir/crash/heap_overflow3
new file mode 100644
index 0000000..c40adbe
--- /dev/null
+++ b/src/testdir/crash/heap_overflow3
Binary files differ
diff --git a/src/testdir/test_crash.vim b/src/testdir/test_crash.vim
index f1843c4..5ec103f 100644
--- a/src/testdir/test_crash.vim
+++ b/src/testdir/test_crash.vim
@@ -216,6 +216,13 @@
   call term_sendkeys(buf, args)
   call TermWait(buf, 50)
 
+  let file = 'crash/heap_overflow3'
+  let cmn_args = "%s -u NONE -i NONE -n -X -m -n -e -s -S %s -c ':qa!'"
+  let args = printf(cmn_args, vim, file)
+  call term_sendkeys(buf, args)
+  call TermWait(buf, 150)
+
+
   " clean up
   exe buf .. "bw!"
   bw!
diff --git a/src/version.c b/src/version.c
index b07964e..7f88c8c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    697,
+/**/
     696,
 /**/
     695,