diff --git a/src/util/rand.c b/src/util/rand.c
index d28e4aa9750..62a997440b1 100644
--- a/src/util/rand.c
+++ b/src/util/rand.c
@@ -15,7 +15,9 @@ See <http://creativecommons.org/publicdomain/zero/1.0/>. */
 #endif
 
 static uint64_t state[4];
+#if defined(GIT_THREADS)
 static git_mutex state_lock;
+#endif
 
 typedef union {
 	double f;