diff --git a/upb/mini_table.c b/upb/mini_table.c
index 8bcaf7449c..af6cb2a860 100644
--- a/upb/mini_table.c
+++ b/upb/mini_table.c
@@ -638,29 +638,26 @@ static void upb_MtDecoder_ParseMessage(upb_MtDecoder* d, const char* data,
   upb_MtDecoder_AllocateSubs(d, sub_count);
 }
 
-#define UPB_COMPARE_INTEGERS(a, b) ((a) < (b) ? -1 : ((a) == (b) ? 0 : 1))
-#define UPB_COMBINE(rep, ty, idx) (((rep << type_bits) | ty) << idx_bits) | idx
-
 int upb_MtDecoder_CompareFields(const void* _a, const void* _b) {
   const upb_LayoutItem* a = _a;
   const upb_LayoutItem* b = _b;
   // Currently we just sort by:
   //  1. rep (smallest fields first)
   //  2. type (oneof cases first)
-  //  2. field_number (smallest numbers first)
+  //  2. field_index (smallest numbers first)
   // The main goal of this is to reduce space lost to padding.
   // Later we may have more subtle reasons to prefer a different ordering.
   const int rep_bits = _upb_Log2Ceiling(kUpb_FieldRep_Max);
   const int type_bits = _upb_Log2Ceiling(kUpb_LayoutItemType_Max);
   const int idx_bits = (sizeof(a->field_index) * 8);
   UPB_ASSERT(idx_bits + rep_bits + type_bits < 32);
+#define UPB_COMBINE(rep, ty, idx) (((rep << type_bits) | ty) << idx_bits) | idx
   uint32_t a_packed = UPB_COMBINE(a->rep, a->type, a->field_index);
   uint32_t b_packed = UPB_COMBINE(b->rep, b->type, b->field_index);
-  return UPB_COMPARE_INTEGERS(a_packed, b_packed);
-}
-
+  assert(a_packed != b_packed);
 #undef UPB_COMBINE
-#undef UPB_COMPARE_INTEGERS
+  return a < b ? -1 : 1;
+}
 
 static bool upb_MtDecoder_SortLayoutItems(upb_MtDecoder* d) {
   // Add items for all non-oneof fields (oneofs were already added).
diff --git a/upb/upb.h b/upb/upb.h
index ba15451229..50bb0cb1cf 100644
--- a/upb/upb.h
+++ b/upb/upb.h
@@ -223,7 +223,7 @@ UPB_INLINE void* upb_Arena_Malloc(upb_Arena* a, size_t size) {
   return ret;
 }
 
-// Call to shrink the last alloc from this arena.
+// Shrinks the last alloc from arena.
 // REQUIRES: (ptr, oldsize) was the last malloc/realloc from this arena.
 // We could also add a upb_Arena_TryShrinkLast() which is simply a no-op if
 // this was not the last alloc.