diff --git a/builtin/grep.c b/builtin/grep.c
index 9ce064ac11..5b881870f6 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -259,6 +259,7 @@ static void start_threads(struct grep_opt *opt)
 	pthread_cond_init(&cond_add, NULL);
 	pthread_cond_init(&cond_write, NULL);
 	pthread_cond_init(&cond_result, NULL);
+	grep_use_locks = 1;
 
 	for (i = 0; i < ARRAY_SIZE(todo); i++) {
 		strbuf_init(&todo[i].out, 0);
@@ -307,6 +308,7 @@ static int wait_all(void)
 	pthread_cond_destroy(&cond_add);
 	pthread_cond_destroy(&cond_write);
 	pthread_cond_destroy(&cond_result);
+	grep_use_locks = 0;
 
 	return hit;
 }
@@ -1030,8 +1032,6 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 	use_threads = 0;
 #endif
 
-	opt.use_threads = use_threads;
-
 #ifndef NO_PTHREADS
 	if (use_threads) {
 		if (opt.pre_context || opt.post_context || opt.file_break ||
diff --git a/grep.c b/grep.c
index 486230b511..7a67c2ff6f 100644
--- a/grep.c
+++ b/grep.c
@@ -807,26 +807,28 @@ static void show_line(struct grep_opt *opt, char *bol, char *eol,
 }
 
 #ifndef NO_PTHREADS
+int grep_use_locks;
+
 /*
  * This lock protects access to the gitattributes machinery, which is
  * not thread-safe.
  */
 pthread_mutex_t grep_attr_mutex;
 
-static inline void grep_attr_lock(struct grep_opt *opt)
+static inline void grep_attr_lock(void)
 {
-	if (opt->use_threads)
+	if (grep_use_locks)
 		pthread_mutex_lock(&grep_attr_mutex);
 }
 
-static inline void grep_attr_unlock(struct grep_opt *opt)
+static inline void grep_attr_unlock(void)
 {
-	if (opt->use_threads)
+	if (grep_use_locks)
 		pthread_mutex_unlock(&grep_attr_mutex);
 }
 #else
-#define grep_attr_lock(opt)
-#define grep_attr_unlock(opt)
+#define grep_attr_lock()
+#define grep_attr_unlock()
 #endif
 
 static int match_funcname(struct grep_opt *opt, const char *name, char *bol, char *eol)
@@ -834,9 +836,9 @@ static int match_funcname(struct grep_opt *opt, const char *name, char *bol, cha
 	xdemitconf_t *xecfg = opt->priv;
 	if (xecfg && !xecfg->find_func) {
 		struct userdiff_driver *drv;
-		grep_attr_lock(opt);
+		grep_attr_lock();
 		drv = userdiff_find_by_path(name);
-		grep_attr_unlock(opt);
+		grep_attr_unlock();
 		if (drv && drv->funcname.pattern) {
 			const struct userdiff_funcname *pe = &drv->funcname;
 			xdiff_set_find_func(xecfg, pe->pattern, pe->cflags);
diff --git a/grep.h b/grep.h
index fb205f3542..3653bb333c 100644
--- a/grep.h
+++ b/grep.h
@@ -116,7 +116,6 @@ struct grep_opt {
 	int show_hunk_mark;
 	int file_break;
 	int heading;
-	int use_threads;
 	void *priv;
 
 	void (*output)(struct grep_opt *opt, const void *data, size_t size);
@@ -138,6 +137,7 @@ extern int grep_threads_ok(const struct grep_opt *opt);
  * Mutex used around access to the attributes machinery if
  * opt->use_threads.  Must be initialized/destroyed by callers!
  */
+extern int grep_use_locks;
 extern pthread_mutex_t grep_attr_mutex;
 #endif