diff --git a/py/gc.c b/py/gc.c
index c763a839ec..c18cd429f3 100644
--- a/py/gc.c
+++ b/py/gc.c
@@ -161,7 +161,7 @@ void gc_init(void *start, void *end) {
     MP_STATE_MEM(gc_alloc_amount) = 0;
     #endif
 
-    #if MICROPY_PY_THREAD
+    #if MICROPY_PY_THREAD && !MICROPY_PY_THREAD_GIL
     mp_thread_mutex_init(&MP_STATE_MEM(gc_mutex));
     #endif
 
diff --git a/py/mpstate.h b/py/mpstate.h
index ab7d8c51b9..9bb87f0ba7 100644
--- a/py/mpstate.h
+++ b/py/mpstate.h
@@ -98,7 +98,7 @@ typedef struct _mp_state_mem_t {
     size_t gc_collected;
     #endif
 
-    #if MICROPY_PY_THREAD
+    #if MICROPY_PY_THREAD && !MICROPY_PY_THREAD_GIL
     // This is a global mutex used to make the GC thread-safe.
     mp_thread_mutex_t gc_mutex;
     #endif