diff --git a/dlls/jscript/jsregexp.c b/dlls/jscript/jsregexp.c
index 9f74e50196c..a47da1fdf17 100644
--- a/dlls/jscript/jsregexp.c
+++ b/dlls/jscript/jsregexp.c
@@ -335,6 +335,7 @@ static HRESULT RegExp_set_lastIndex(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t
 
     TRACE("\n");
 
+    jsval_release(regexp->last_index_val);
     hres = jsval_copy(value, &regexp->last_index_val);
     if(FAILED(hres))
         return hres;