diff --git a/src/eval.c b/src/eval.c
index 273ac41..01610fe 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -8252,6 +8252,12 @@
 	EMSG(_("E785: complete() can only be used in Insert mode"));
 	return;
     }
+
+    /* Check for undo allowed here, because if something was already inserted
+     * the line was already saved for undo and this check isn't done. */
+    if (!undo_allowed())
+	return;
+
     if (argvars[1].v_type != VAR_LIST || argvars[1].vval.v_list == NULL)
     {
 	EMSG(_(e_invarg));
diff --git a/src/proto/undo.pro b/src/proto/undo.pro
index c48e65c..1397dc5 100644
--- a/src/proto/undo.pro
+++ b/src/proto/undo.pro
@@ -4,6 +4,7 @@
 extern int u_savesub __ARGS((linenr_T lnum));
 extern int u_inssub __ARGS((linenr_T lnum));
 extern int u_savedel __ARGS((linenr_T lnum, long nlines));
+extern int undo_allowed __ARGS((void));
 extern void u_undo __ARGS((int count));
 extern void u_redo __ARGS((int count));
 extern void undo_time __ARGS((long step, int sec, int absolute));
diff --git a/src/undo.c b/src/undo.c
index fd1bcc7..6a98641 100644
--- a/src/undo.c
+++ b/src/undo.c
@@ -84,7 +84,6 @@
 static void u_unch_branch __ARGS((u_header_T *uhp));
 static u_entry_T *u_get_headentry __ARGS((void));
 static void u_getbot __ARGS((void));
-static int undo_allowed __ARGS((void));
 static int u_savecommon __ARGS((linenr_T, linenr_T, linenr_T));
 static void u_doit __ARGS((int count));
 static void u_undoredo __ARGS((int undo));
@@ -196,7 +195,7 @@
  * Return TRUE when undo is allowed.  Otherwise give an error message and
  * return FALSE.
  */
-    static int
+    int
 undo_allowed()
 {
     /* Don't allow changes when 'modifiable' is off.  */
diff --git a/src/version.c b/src/version.c
index 8c03ce8..bee5a39 100644
--- a/src/version.c
+++ b/src/version.c
@@ -667,6 +667,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    38,
+/**/
     37,
 /**/
     36,