diff --git a/gc.c b/gc.c
index a1e6bc4bc2..ad4cd55b2a 100644
--- a/gc.c
+++ b/gc.c
@@ -3996,6 +3996,11 @@ init_mark_stack(mark_stack_t *stack)
 #define STACK_END (ec->machine.stack_end)
 #define STACK_LEVEL_MAX (ec->machine.stack_maxsize/sizeof(VALUE))
 
+#ifdef __EMSCRIPTEN__
+#undef STACK_GROW_DIRECTION
+#define STACK_GROW_DIRECTION 1
+#endif
+
 #if STACK_GROW_DIRECTION < 0
 # define STACK_LENGTH  (size_t)(STACK_START - STACK_END)
 #elif STACK_GROW_DIRECTION > 0