diff --git a/src/regexp.c b/src/regexp.c
index ef3896c..7aeddb8 100644
--- a/src/regexp.c
+++ b/src/regexp.c
@@ -2663,6 +2663,15 @@
 }
 #endif
 
+/*
+ * Free the previously used substitute search pattern.
+ */
+    void
+free_regexp_prev_sub(void)
+{
+    VIM_CLEAR(reg_prev_sub);
+}
+
 #ifdef FEAT_EVAL
     static void
 report_re_switch(char_u *pat)