diff --git a/src/bitmap.c b/src/bitmap.c
index a94e15cf..68ae3b2e 100644
--- a/src/bitmap.c
+++ b/src/bitmap.c
@@ -179,7 +179,7 @@ static bool mi_bitmap_try_find_claim_field_across(mi_bitmap_t bitmap, size_t bit
   _Atomic(uintptr_t)* field = &bitmap[idx];
   uintptr_t map = mi_atomic_load_relaxed(field);  
   const size_t initial = mi_clz(map);  // count of initial zeros starting at idx
-  mi_assert_internal(initial >= 0 && initial <= MI_BITMAP_FIELD_BITS);
+  mi_assert_internal(initial <= MI_BITMAP_FIELD_BITS);
   if (initial == 0)     return false;
   if (initial >= count) return _mi_bitmap_try_find_claim_field(bitmap, idx, count, bitmap_idx);     // no need to cross fields
   if (_mi_divide_up(count - initial, MI_BITMAP_FIELD_BITS) >= (bitmap_fields - idx)) return false; // not enough entries