diff --git a/src/optionstr.c b/src/optionstr.c
index 705e860..8948830 100644
--- a/src/optionstr.c
+++ b/src/optionstr.c
@@ -2333,6 +2333,15 @@
     }
 #endif
 
+#ifdef FEAT_EVAL
+    // 'tagfunc'
+    else if (gvarp == &p_tfu)
+    {
+	if (set_tagfunc_option() == FAIL)
+	    errmsg = e_invarg;
+    }
+#endif
+
     // Options that are a list of flags.
     else
     {