diff --git a/src/debugger.c b/src/debugger.c
index 4a32550..09c8355 100644
--- a/src/debugger.c
+++ b/src/debugger.c
@@ -87,6 +87,7 @@
     msg_silent = FALSE;		// display messages
     emsg_silent = FALSE;	// display error messages
     redir_off = TRUE;		// don't redirect debug commands
+    save_timeout_for_debugging();   // disable  regexp timeout flag
 
     State = MODE_NORMAL;
     debug_mode = TRUE;
@@ -293,6 +294,7 @@
     redraw_all_later(UPD_NOT_VALID);
     need_wait_return = FALSE;
     msg_scroll = save_msg_scroll;
+    restore_timeout_for_debugging();
     lines_left = Rows - 1;
     State = save_State;
     debug_mode = FALSE;
diff --git a/src/proto/regexp.pro b/src/proto/regexp.pro
index 3fd91ee..ffd5a07 100644
--- a/src/proto/regexp.pro
+++ b/src/proto/regexp.pro
@@ -1,6 +1,8 @@
 /* regexp.c */
 void init_regexp_timeout(long msec);
 void disable_regexp_timeout(void);
+void save_timeout_for_debugging(void);
+void restore_timeout_for_debugging(void);
 int re_multiline(regprog_T *prog);
 char_u *skip_regexp(char_u *startp, int delim, int magic);
 char_u *skip_regexp_err(char_u *startp, int delim, int magic);
diff --git a/src/regexp.c b/src/regexp.c
index 61fc14d..842c480 100644
--- a/src/regexp.c
+++ b/src/regexp.c
@@ -80,6 +80,34 @@
 }
 #endif
 
+#if defined(FEAT_EVAL) || defined(PROTO)
+# ifdef FEAT_RELTIME
+static sig_atomic_t *saved_timeout_flag;
+# endif
+
+/*
+ * Used at the debug prompt: disable the timeout so that expression evaluation
+ * can used patterns.
+ * Must be followed by calling restore_timeout_for_debugging().
+ */
+    void
+save_timeout_for_debugging(void)
+{
+# ifdef FEAT_RELTIME
+    saved_timeout_flag = (sig_atomic_t *)timeout_flag;
+    timeout_flag = &dummy_timeout_flag;
+# endif
+}
+
+    void
+restore_timeout_for_debugging(void)
+{
+# ifdef FEAT_RELTIME
+    timeout_flag = saved_timeout_flag;
+# endif
+}
+#endif
+
 /*
  * The first byte of the BT regexp internal "program" is actually this magic
  * number; the start node begins in the second byte.  It's used to catch the
diff --git a/src/version.c b/src/version.c
index 55da620..129f7ce 100644
--- a/src/version.c
+++ b/src/version.c
@@ -700,6 +700,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    513,
+/**/
     512,
 /**/
     511,