diff --git a/mergetools/tkdiff b/mergetools/tkdiff
--- /dev/null
+++ b/mergetools/tkdiff
@@ -0,0 +1,12 @@
+diff_cmd () {
+ "$merge_tool_path" "$LOCAL" "$REMOTE"
+}
+
+merge_cmd () {
+ if $base_present
+ then
+ "$merge_tool_path" -a "$BASE" -o "$MERGED" "$LOCAL" "$REMOTE"
+ else
+ "$merge_tool_path" -o "$MERGED" "$LOCAL" "$REMOTE"
+ fi
+}