#include "tree-walk.h"
 #include "xdiff-interface.h"
 #include "blob.h"
+#include "exec_cmd.h"
 
-static const char merge_tree_usage[] = "git-merge-tree <base-tree> <branch1> <branch2>";
+static const char merge_tree_usage[] = "git merge-tree <base-tree> <branch1> <branch2>";
 static int resolve_directories = 1;
 
 struct merge_list {
        if (argc != 4)
                usage(merge_tree_usage);
 
+       git_extract_argv0_path(argv[0]);
+
        setup_git_directory();
 
        buf1 = get_tree_descriptor(t+0, argv[1]);