diff --git a/python/descriptor.c b/python/descriptor.c
index 815157c7a9..007ee61212 100644
--- a/python/descriptor.c
+++ b/python/descriptor.c
@@ -392,7 +392,7 @@ static PyObject* PyUpb_Descriptor_GetFieldsByNumber(PyObject* _self,
           (void*)&upb_MessageDef_Field,
           (void*)&PyUpb_FieldDescriptor_Get,
       },
-      (void*)&upb_MessageDef_FindFieldByNumberWithSize,
+      (void*)&upb_MessageDef_FindFieldByNumber,
       (void*)&upb_FieldDef_Number,
   };
   PyUpb_DescriptorBase* self = (void*)_self;
diff --git a/rename.sed b/rename.sed
index 771bf74ae2..a4b6dbf2ae 100644
--- a/rename.sed
+++ b/rename.sed
@@ -71,7 +71,7 @@ s/upb_msgdef_field/upb_MessageDef_Field/g;
 s/upb_msgdef_oneof/upb_MessageDef_Oneof/g;
 s/upb_msgdef_ntooz/upb_MessageDef_FindOneofByName/g;
 s/upb_msgdef_ntofz/upb_MessageDef_FindFieldByName/g;
-s/upb_msgdef_itof/upb_MessageDef_FindFieldByNumberWithSize/g;
+s/upb_msgdef_itof/upb_MessageDef_FindFieldByNumber/g;
 s/upb_msgdef_ntof/upb_MessageDef_FindFieldByNameWithSize/g;
 s/upb_msgdef_ntoo/upb_MessageDef_FindOneofByNameWithSize/g;
 s/upb_msgdef_layout/upb_MessageDef_MiniTable/g;
@@ -89,6 +89,7 @@ s/upb_msgdef_lookupjsonnamez/upb_MessageDef_FindByNameName/g;
 s/upb_msgdef_lookupjsonname/upb_MessageDef_FindByJsonNameWithSize/g;
 s/upb_msgdef/upb_MessageDef/g;
 s/WithSizez//g;
+s/upb_MessageDef_FindFieldByNumberWithSize/upb_MessageDef_FindFieldByNumber/g;
 
 s/upb_extrange_options/upb_ExtensionRange_Options/g;
 s/upb_extrange_hasoptions/upb_ExtensionRange_HasOptions/g;
diff --git a/upb/bindings/lua/def.c b/upb/bindings/lua/def.c
index 6716b26a72..132116719a 100644
--- a/upb/bindings/lua/def.c
+++ b/upb/bindings/lua/def.c
@@ -368,7 +368,7 @@ static int lupb_MessageDef_Field(lua_State* L) {
 
   switch (lua_type(L, 2)) {
     case LUA_TNUMBER:
-      f = upb_MessageDef_FindFieldByNumberWithSize(m, lua_tointeger(L, 2));
+      f = upb_MessageDef_FindFieldByNumber(m, lua_tointeger(L, 2));
       break;
     case LUA_TSTRING:
       f = upb_MessageDef_FindFieldByName(m, lua_tostring(L, 2));
diff --git a/upb/bindings/lua/msg.c b/upb/bindings/lua/msg.c
index dd846570d9..a314f4dbee 100644
--- a/upb/bindings/lua/msg.c
+++ b/upb/bindings/lua/msg.c
@@ -733,10 +733,10 @@ static void lupb_Message_Newwrapper(lua_State* L, int narg,
                                     upb_MutableMessageValue val) {
   if (upb_FieldDef_IsMap(f)) {
     const upb_MessageDef* entry = upb_FieldDef_MessageSubDef(f);
-    const upb_FieldDef* key_f = upb_MessageDef_FindFieldByNumberWithSize(
-        entry, kUpb_MapEntry_KeyFieldNumber);
-    const upb_FieldDef* val_f = upb_MessageDef_FindFieldByNumberWithSize(
-        entry, kUpb_MapEntry_ValueFieldNumber);
+    const upb_FieldDef* key_f =
+        upb_MessageDef_FindFieldByNumber(entry, kUpb_MapEntry_KeyFieldNumber);
+    const upb_FieldDef* val_f =
+        upb_MessageDef_FindFieldByNumber(entry, kUpb_MapEntry_ValueFieldNumber);
     lupb_map* lmap =
         lupb_Message_Newud(L, narg, sizeof(*lmap), LUPB_MAP, val_f);
     lmap->key_type = upb_FieldDef_CType(key_f);
@@ -849,10 +849,10 @@ static int lupb_Message_Newindex(lua_State* L) {
   if (upb_FieldDef_IsMap(f)) {
     lupb_map* lmap = lupb_map_check(L, 3);
     const upb_MessageDef* entry = upb_FieldDef_MessageSubDef(f);
-    const upb_FieldDef* key_f = upb_MessageDef_FindFieldByNumberWithSize(
-        entry, kUpb_MapEntry_KeyFieldNumber);
-    const upb_FieldDef* val_f = upb_MessageDef_FindFieldByNumberWithSize(
-        entry, kUpb_MapEntry_ValueFieldNumber);
+    const upb_FieldDef* key_f =
+        upb_MessageDef_FindFieldByNumber(entry, kUpb_MapEntry_KeyFieldNumber);
+    const upb_FieldDef* val_f =
+        upb_MessageDef_FindFieldByNumber(entry, kUpb_MapEntry_ValueFieldNumber);
     upb_CType key_type = upb_FieldDef_CType(key_f);
     upb_CType value_type = upb_FieldDef_CType(val_f);
     luaL_argcheck(L, lmap->key_type == key_type, 3, "key type mismatch");
diff --git a/upb/def.c b/upb/def.c
index 9fe8c7e9fa..363d8bb960 100644
--- a/upb/def.c
+++ b/upb/def.c
@@ -691,8 +691,8 @@ upb_Syntax upb_MessageDef_Syntax(const upb_MessageDef* m) {
   return m->file->syntax;
 }
 
-const upb_FieldDef* upb_MessageDef_FindFieldByNumberWithSize(
-    const upb_MessageDef* m, uint32_t i) {
+const upb_FieldDef* upb_MessageDef_FindFieldByNumber(const upb_MessageDef* m,
+                                                     uint32_t i) {
   upb_value val;
   return upb_inttable_lookup(&m->itof, i, &val) ? upb_value_getconstptr(val)
                                                 : NULL;
@@ -1365,8 +1365,8 @@ static void assign_layout_indices(const upb_MessageDef* m, upb_MiniTable* l,
   int n = upb_MessageDef_numfields(m);
   int dense_below = 0;
   for (i = 0; i < n; i++) {
-    upb_FieldDef* f = (upb_FieldDef*)upb_MessageDef_FindFieldByNumberWithSize(
-        m, fields[i].number);
+    upb_FieldDef* f =
+        (upb_FieldDef*)upb_MessageDef_FindFieldByNumber(m, fields[i].number);
     UPB_ASSERT(f);
     f->layout_index = i;
     if (i < UINT8_MAX && fields[i].number == i + 1 &&
@@ -1487,8 +1487,8 @@ static void make_layout(symtab_addctx* ctx, const upb_MessageDef* m) {
   if (upb_MessageDef_IsMapEntry(m)) {
     /* TODO(haberman): refactor this method so this special case is more
      * elegant. */
-    const upb_FieldDef* key = upb_MessageDef_FindFieldByNumberWithSize(m, 1);
-    const upb_FieldDef* val = upb_MessageDef_FindFieldByNumberWithSize(m, 2);
+    const upb_FieldDef* key = upb_MessageDef_FindFieldByNumber(m, 1);
+    const upb_FieldDef* val = upb_MessageDef_FindFieldByNumber(m, 2);
     fields[0].number = 1;
     fields[1].number = 2;
     fields[0].mode = kUpb_FieldMode_Scalar;
diff --git a/upb/def.h b/upb/def.h
index 895aa1a90e..8b64a53c1d 100644
--- a/upb/def.h
+++ b/upb/def.h
@@ -188,8 +188,8 @@ const upb_ExtensionRange* upb_MessageDef_ExtensionRange(const upb_MessageDef* m,
                                                         int i);
 const upb_FieldDef* upb_MessageDef_Field(const upb_MessageDef* m, int i);
 const upb_OneofDef* upb_MessageDef_Oneof(const upb_MessageDef* m, int i);
-const upb_FieldDef* upb_MessageDef_FindFieldByNumberWithSize(
-    const upb_MessageDef* m, uint32_t i);
+const upb_FieldDef* upb_MessageDef_FindFieldByNumber(const upb_MessageDef* m,
+                                                     uint32_t i);
 const upb_FieldDef* upb_MessageDef_FindFieldByNameWithSize(
     const upb_MessageDef* m, const char* name, size_t len);
 const upb_OneofDef* upb_MessageDef_FindOneofByNameWithSize(
diff --git a/upb/def.hpp b/upb/def.hpp
index 0fd093bbcd..aaf9496226 100644
--- a/upb/def.hpp
+++ b/upb/def.hpp
@@ -194,7 +194,7 @@ class MessageDefPtr {
 
   // These return null pointers if the field is not found.
   FieldDefPtr FindFieldByNumber(uint32_t number) const {
-    return FieldDefPtr(upb_MessageDef_FindFieldByNumberWithSize(ptr_, number));
+    return FieldDefPtr(upb_MessageDef_FindFieldByNumber(ptr_, number));
   }
   FieldDefPtr FindFieldByName(const char* name, size_t len) const {
     return FieldDefPtr(upb_MessageDef_FindFieldByNameWithSize(ptr_, name, len));
diff --git a/upb/json_decode.c b/upb/json_decode.c
index 566e9d4a1b..c4698f03bf 100644
--- a/upb/json_decode.c
+++ b/upb/json_decode.c
@@ -894,10 +894,8 @@ static void jsondec_array(jsondec* d, upb_Message* msg, const upb_FieldDef* f) {
 static void jsondec_map(jsondec* d, upb_Message* msg, const upb_FieldDef* f) {
   upb_Map* map = upb_Message_Mutable(msg, f, d->arena).map;
   const upb_MessageDef* entry = upb_FieldDef_MessageSubDef(f);
-  const upb_FieldDef* key_f =
-      upb_MessageDef_FindFieldByNumberWithSize(entry, 1);
-  const upb_FieldDef* val_f =
-      upb_MessageDef_FindFieldByNumberWithSize(entry, 2);
+  const upb_FieldDef* key_f = upb_MessageDef_FindFieldByNumber(entry, 1);
+  const upb_FieldDef* val_f = upb_MessageDef_FindFieldByNumber(entry, 2);
 
   jsondec_objstart(d);
   while (jsondec_objnext(d)) {
@@ -1139,10 +1137,9 @@ static void jsondec_timestamp(jsondec* d, upb_Message* msg,
     jsondec_err(d, "Timestamp out of range");
   }
 
-  upb_Message_Set(msg, upb_MessageDef_FindFieldByNumberWithSize(m, 1), seconds,
-                  d->arena);
-  upb_Message_Set(msg, upb_MessageDef_FindFieldByNumberWithSize(m, 2), nanos,
+  upb_Message_Set(msg, upb_MessageDef_FindFieldByNumber(m, 1), seconds,
                   d->arena);
+  upb_Message_Set(msg, upb_MessageDef_FindFieldByNumber(m, 2), nanos, d->arena);
   return;
 
 malformed:
@@ -1174,15 +1171,14 @@ static void jsondec_duration(jsondec* d, upb_Message* msg,
     nanos.int32_val = -nanos.int32_val;
   }
 
-  upb_Message_Set(msg, upb_MessageDef_FindFieldByNumberWithSize(m, 1), seconds,
-                  d->arena);
-  upb_Message_Set(msg, upb_MessageDef_FindFieldByNumberWithSize(m, 2), nanos,
+  upb_Message_Set(msg, upb_MessageDef_FindFieldByNumber(m, 1), seconds,
                   d->arena);
+  upb_Message_Set(msg, upb_MessageDef_FindFieldByNumber(m, 2), nanos, d->arena);
 }
 
 static void jsondec_listvalue(jsondec* d, upb_Message* msg,
                               const upb_MessageDef* m) {
-  const upb_FieldDef* values_f = upb_MessageDef_FindFieldByNumberWithSize(m, 1);
+  const upb_FieldDef* values_f = upb_MessageDef_FindFieldByNumber(m, 1);
   const upb_MessageDef* value_m = upb_FieldDef_MessageSubDef(values_f);
   upb_Array* values = upb_Message_Mutable(msg, values_f, d->arena).array;
 
@@ -1199,10 +1195,9 @@ static void jsondec_listvalue(jsondec* d, upb_Message* msg,
 
 static void jsondec_struct(jsondec* d, upb_Message* msg,
                            const upb_MessageDef* m) {
-  const upb_FieldDef* fields_f = upb_MessageDef_FindFieldByNumberWithSize(m, 1);
+  const upb_FieldDef* fields_f = upb_MessageDef_FindFieldByNumber(m, 1);
   const upb_MessageDef* entry_m = upb_FieldDef_MessageSubDef(fields_f);
-  const upb_FieldDef* value_f =
-      upb_MessageDef_FindFieldByNumberWithSize(entry_m, 2);
+  const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumber(entry_m, 2);
   const upb_MessageDef* value_m = upb_FieldDef_MessageSubDef(value_f);
   upb_Map* fields = upb_Message_Mutable(msg, fields_f, d->arena).map;
 
@@ -1228,42 +1223,42 @@ static void jsondec_wellknownvalue(jsondec* d, upb_Message* msg,
   switch (jsondec_peek(d)) {
     case JD_NUMBER:
       /* double number_value = 2; */
-      f = upb_MessageDef_FindFieldByNumberWithSize(m, 2);
+      f = upb_MessageDef_FindFieldByNumber(m, 2);
       val.double_val = jsondec_number(d);
       break;
     case JD_STRING:
       /* string string_value = 3; */
-      f = upb_MessageDef_FindFieldByNumberWithSize(m, 3);
+      f = upb_MessageDef_FindFieldByNumber(m, 3);
       val.str_val = jsondec_string(d);
       break;
     case JD_FALSE:
       /* bool bool_value = 4; */
-      f = upb_MessageDef_FindFieldByNumberWithSize(m, 4);
+      f = upb_MessageDef_FindFieldByNumber(m, 4);
       val.bool_val = false;
       jsondec_false(d);
       break;
     case JD_TRUE:
       /* bool bool_value = 4; */
-      f = upb_MessageDef_FindFieldByNumberWithSize(m, 4);
+      f = upb_MessageDef_FindFieldByNumber(m, 4);
       val.bool_val = true;
       jsondec_true(d);
       break;
     case JD_NULL:
       /* NullValue null_value = 1; */
-      f = upb_MessageDef_FindFieldByNumberWithSize(m, 1);
+      f = upb_MessageDef_FindFieldByNumber(m, 1);
       val.int32_val = 0;
       jsondec_null(d);
       break;
     /* Note: these cases return, because upb_Message_Mutable() is enough. */
     case JD_OBJECT:
       /* Struct struct_value = 5; */
-      f = upb_MessageDef_FindFieldByNumberWithSize(m, 5);
+      f = upb_MessageDef_FindFieldByNumber(m, 5);
       submsg = upb_Message_Mutable(msg, f, d->arena).msg;
       jsondec_struct(d, submsg, upb_FieldDef_MessageSubDef(f));
       return;
     case JD_ARRAY:
       /* ListValue list_value = 6; */
-      f = upb_MessageDef_FindFieldByNumberWithSize(m, 6);
+      f = upb_MessageDef_FindFieldByNumber(m, 6);
       submsg = upb_Message_Mutable(msg, f, d->arena).msg;
       jsondec_listvalue(d, submsg, upb_FieldDef_MessageSubDef(f));
       return;
@@ -1310,7 +1305,7 @@ static upb_StringView jsondec_mask(jsondec* d, const char* buf,
 static void jsondec_fieldmask(jsondec* d, upb_Message* msg,
                               const upb_MessageDef* m) {
   /* repeated string paths = 1; */
-  const upb_FieldDef* paths_f = upb_MessageDef_FindFieldByNumberWithSize(m, 1);
+  const upb_FieldDef* paths_f = upb_MessageDef_FindFieldByNumber(m, 1);
   upb_Array* arr = upb_Message_Mutable(msg, paths_f, d->arena).array;
   upb_StringView str = jsondec_string(d);
   const char* ptr = str.data;
@@ -1350,8 +1345,7 @@ static void jsondec_anyfield(jsondec* d, upb_Message* msg,
 
 static const upb_MessageDef* jsondec_typeurl(jsondec* d, upb_Message* msg,
                                              const upb_MessageDef* m) {
-  const upb_FieldDef* type_url_f =
-      upb_MessageDef_FindFieldByNumberWithSize(m, 1);
+  const upb_FieldDef* type_url_f = upb_MessageDef_FindFieldByNumber(m, 1);
   const upb_MessageDef* type_m;
   upb_StringView type_url = jsondec_string(d);
   const char* end = type_url.data + type_url.size;
@@ -1382,7 +1376,7 @@ static const upb_MessageDef* jsondec_typeurl(jsondec* d, upb_Message* msg,
 static void jsondec_any(jsondec* d, upb_Message* msg, const upb_MessageDef* m) {
   /* string type_url = 1;
    * bytes value = 2; */
-  const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumberWithSize(m, 2);
+  const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumber(m, 2);
   upb_Message* any_msg;
   const upb_MessageDef* any_m = NULL;
   const char* pre_type_data = NULL;
@@ -1444,7 +1438,7 @@ static void jsondec_any(jsondec* d, upb_Message* msg, const upb_MessageDef* m) {
 
 static void jsondec_wrapper(jsondec* d, upb_Message* msg,
                             const upb_MessageDef* m) {
-  const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumberWithSize(m, 1);
+  const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumber(m, 1);
   upb_MessageValue val = jsondec_value(d, value_f);
   upb_Message_Set(msg, value_f, val, d->arena);
 }
diff --git a/upb/json_encode.c b/upb/json_encode.c
index e0b35f1320..9668a426d2 100644
--- a/upb/json_encode.c
+++ b/upb/json_encode.c
@@ -141,9 +141,8 @@ static void jsonenc_nanos(jsonenc* e, int32_t nanos) {
 
 static void jsonenc_timestamp(jsonenc* e, const upb_Message* msg,
                               const upb_MessageDef* m) {
-  const upb_FieldDef* seconds_f =
-      upb_MessageDef_FindFieldByNumberWithSize(m, 1);
-  const upb_FieldDef* nanos_f = upb_MessageDef_FindFieldByNumberWithSize(m, 2);
+  const upb_FieldDef* seconds_f = upb_MessageDef_FindFieldByNumber(m, 1);
+  const upb_FieldDef* nanos_f = upb_MessageDef_FindFieldByNumber(m, 2);
   int64_t seconds = upb_Message_Get(msg, seconds_f).int64_val;
   int32_t nanos = upb_Message_Get(msg, nanos_f).int32_val;
   int L, N, I, J, K, hour, min, sec;
@@ -185,9 +184,8 @@ static void jsonenc_timestamp(jsonenc* e, const upb_Message* msg,
 
 static void jsonenc_duration(jsonenc* e, const upb_Message* msg,
                              const upb_MessageDef* m) {
-  const upb_FieldDef* seconds_f =
-      upb_MessageDef_FindFieldByNumberWithSize(m, 1);
-  const upb_FieldDef* nanos_f = upb_MessageDef_FindFieldByNumberWithSize(m, 2);
+  const upb_FieldDef* seconds_f = upb_MessageDef_FindFieldByNumber(m, 1);
+  const upb_FieldDef* nanos_f = upb_MessageDef_FindFieldByNumber(m, 2);
   int64_t seconds = upb_Message_Get(msg, seconds_f).int64_val;
   int32_t nanos = upb_Message_Get(msg, nanos_f).int32_val;
 
@@ -336,7 +334,7 @@ static void upb_JsonEncode_Float(jsonenc* e, float val) {
 
 static void jsonenc_wrapper(jsonenc* e, const upb_Message* msg,
                             const upb_MessageDef* m) {
-  const upb_FieldDef* val_f = upb_MessageDef_FindFieldByNumberWithSize(m, 1);
+  const upb_FieldDef* val_f = upb_MessageDef_FindFieldByNumber(m, 1);
   upb_MessageValue val = upb_Message_Get(msg, val_f);
   jsonenc_scalar(e, val, val_f);
 }
@@ -380,9 +378,8 @@ badurl:
 
 static void jsonenc_any(jsonenc* e, const upb_Message* msg,
                         const upb_MessageDef* m) {
-  const upb_FieldDef* type_url_f =
-      upb_MessageDef_FindFieldByNumberWithSize(m, 1);
-  const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumberWithSize(m, 2);
+  const upb_FieldDef* type_url_f = upb_MessageDef_FindFieldByNumber(m, 1);
+  const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumber(m, 2);
   upb_StringView type_url = upb_Message_Get(msg, type_url_f).str_val;
   upb_StringView value = upb_Message_Get(msg, value_f).str_val;
   const upb_MessageDef* any_m = jsonenc_getanymsg(e, type_url);
@@ -441,7 +438,7 @@ static void jsonenc_fieldpath(jsonenc* e, upb_StringView path) {
 
 static void jsonenc_fieldmask(jsonenc* e, const upb_Message* msg,
                               const upb_MessageDef* m) {
-  const upb_FieldDef* paths_f = upb_MessageDef_FindFieldByNumberWithSize(m, 1);
+  const upb_FieldDef* paths_f = upb_MessageDef_FindFieldByNumber(m, 1);
   const upb_Array* paths = upb_Message_Get(msg, paths_f).array_val;
   bool first = true;
   size_t i, n = 0;
@@ -460,11 +457,10 @@ static void jsonenc_fieldmask(jsonenc* e, const upb_Message* msg,
 
 static void jsonenc_struct(jsonenc* e, const upb_Message* msg,
                            const upb_MessageDef* m) {
-  const upb_FieldDef* fields_f = upb_MessageDef_FindFieldByNumberWithSize(m, 1);
+  const upb_FieldDef* fields_f = upb_MessageDef_FindFieldByNumber(m, 1);
   const upb_Map* fields = upb_Message_Get(msg, fields_f).map_val;
   const upb_MessageDef* entry_m = upb_FieldDef_MessageSubDef(fields_f);
-  const upb_FieldDef* value_f =
-      upb_MessageDef_FindFieldByNumberWithSize(entry_m, 2);
+  const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumber(entry_m, 2);
   size_t iter = kUpb_Map_Begin;
   bool first = true;
 
@@ -487,7 +483,7 @@ static void jsonenc_struct(jsonenc* e, const upb_Message* msg,
 
 static void jsonenc_listvalue(jsonenc* e, const upb_Message* msg,
                               const upb_MessageDef* m) {
-  const upb_FieldDef* values_f = upb_MessageDef_FindFieldByNumberWithSize(m, 1);
+  const upb_FieldDef* values_f = upb_MessageDef_FindFieldByNumber(m, 1);
   const upb_MessageDef* values_m = upb_FieldDef_MessageSubDef(values_f);
   const upb_Array* values = upb_Message_Get(msg, values_f).array_val;
   size_t i;
@@ -669,10 +665,8 @@ static void jsonenc_array(jsonenc* e, const upb_Array* arr,
 
 static void jsonenc_map(jsonenc* e, const upb_Map* map, const upb_FieldDef* f) {
   const upb_MessageDef* entry = upb_FieldDef_MessageSubDef(f);
-  const upb_FieldDef* key_f =
-      upb_MessageDef_FindFieldByNumberWithSize(entry, 1);
-  const upb_FieldDef* val_f =
-      upb_MessageDef_FindFieldByNumberWithSize(entry, 2);
+  const upb_FieldDef* key_f = upb_MessageDef_FindFieldByNumber(entry, 1);
+  const upb_FieldDef* val_f = upb_MessageDef_FindFieldByNumber(entry, 2);
   size_t iter = kUpb_Map_Begin;
   bool first = true;
 
diff --git a/upb/reflection.c b/upb/reflection.c
index dca1ec25a6..a3a64d2780 100644
--- a/upb/reflection.c
+++ b/upb/reflection.c
@@ -180,10 +180,10 @@ make:
   if (!a) return (upb_MutableMessageValue){.array = NULL};
   if (upb_FieldDef_IsMap(f)) {
     const upb_MessageDef* entry = upb_FieldDef_MessageSubDef(f);
-    const upb_FieldDef* key = upb_MessageDef_FindFieldByNumberWithSize(
-        entry, kUpb_MapEntry_KeyFieldNumber);
-    const upb_FieldDef* value = upb_MessageDef_FindFieldByNumberWithSize(
-        entry, kUpb_MapEntry_ValueFieldNumber);
+    const upb_FieldDef* key =
+        upb_MessageDef_FindFieldByNumber(entry, kUpb_MapEntry_KeyFieldNumber);
+    const upb_FieldDef* value =
+        upb_MessageDef_FindFieldByNumber(entry, kUpb_MapEntry_ValueFieldNumber);
     ret.map =
         upb_Map_New(a, upb_FieldDef_CType(key), upb_FieldDef_CType(value));
   } else if (upb_FieldDef_IsRepeated(f)) {
@@ -313,8 +313,7 @@ bool _upb_Message_DiscardUnknown(upb_Message* msg, const upb_MessageDef* m,
     const upb_MessageDef* subm = upb_FieldDef_MessageSubDef(f);
     if (!subm) continue;
     if (upb_FieldDef_IsMap(f)) {
-      const upb_FieldDef* val_f =
-          upb_MessageDef_FindFieldByNumberWithSize(subm, 2);
+      const upb_FieldDef* val_f = upb_MessageDef_FindFieldByNumber(subm, 2);
       const upb_MessageDef* val_m = upb_FieldDef_MessageSubDef(val_f);
       upb_Map* map = (upb_Map*)val.map_val;
       size_t iter = kUpb_Map_Begin;