diff --git a/py/gc.c b/py/gc.c
index ac584d5d20..a8a5fde125 100755
--- a/py/gc.c
+++ b/py/gc.c
@@ -53,9 +53,6 @@
 // detect untraced object still in use
 #define CLEAR_ON_SWEEP (0)
 
-#define WORDS_PER_BLOCK ((MICROPY_BYTES_PER_GC_BLOCK) / BYTES_PER_WORD)
-#define BYTES_PER_BLOCK (MICROPY_BYTES_PER_GC_BLOCK)
-
 // ATB = allocation table byte
 // 0b00 = FREE -- free block
 // 0b01 = HEAD -- head of a chain of blocks
@@ -209,13 +206,6 @@ bool gc_is_locked(void) {
     return MP_STATE_MEM(gc_lock_depth) != 0;
 }
 
-// ptr should be of type void*
-#define VERIFY_PTR(ptr) ( \
-        ((uintptr_t)(ptr) & (BYTES_PER_BLOCK - 1)) == 0      /* must be aligned on a block */ \
-        && ptr >= (void*)MP_STATE_MEM(gc_pool_start)     /* must be above start of pool */ \
-        && ptr < (void*)MP_STATE_MEM(gc_pool_end)        /* must be below end of pool */ \
-    )
-
 #ifndef TRACE_MARK
 #if DEBUG_PRINT
 #define TRACE_MARK(block, ptr) DEBUG_printf("gc_mark(%p)\n", ptr)
diff --git a/py/gc.h b/py/gc.h
index 02bf451587..cd63ba94cf 100644
--- a/py/gc.h
+++ b/py/gc.h
@@ -29,8 +29,19 @@
 #include <stdint.h>
 
 #include "py/mpconfig.h"
+#include "py/mpstate.h"
 #include "py/misc.h"
 
+#define WORDS_PER_BLOCK ((MICROPY_BYTES_PER_GC_BLOCK) / BYTES_PER_WORD)
+#define BYTES_PER_BLOCK (MICROPY_BYTES_PER_GC_BLOCK)
+
+// ptr should be of type void*
+#define VERIFY_PTR(ptr) ( \
+        ((uintptr_t)(ptr) & (BYTES_PER_BLOCK - 1)) == 0      /* must be aligned on a block */ \
+        && ptr >= (void*)MP_STATE_MEM(gc_pool_start)     /* must be above start of pool */ \
+        && ptr < (void*)MP_STATE_MEM(gc_pool_end)        /* must be below end of pool */ \
+    )
+
 void gc_init(void *start, void *end);
 void gc_deinit(void);
 
diff --git a/py/gc_long_lived.c b/py/gc_long_lived.c
index 49bf1fcd79..01c22a7af7 100755
--- a/py/gc_long_lived.c
+++ b/py/gc_long_lived.c
@@ -126,6 +126,11 @@ mp_obj_t make_obj_long_lived(mp_obj_t obj, uint8_t max_depth){
     if (obj == NULL) {
         return obj;
     }
+    // If not in the GC pool, do nothing. This can happen (at least) when
+    // there are frozen mp_type_bytes objects in ROM.
+    if (!VERIFY_PTR((void *)obj)) {
+        return obj;
+    }
     if (MP_OBJ_IS_TYPE(obj, &mp_type_fun_bc)) {
         mp_obj_fun_bc_t *fun_bc = MP_OBJ_TO_PTR(obj);
         return MP_OBJ_FROM_PTR(make_fun_bc_long_lived(fun_bc, max_depth));