diff --git a/runtime/pb/json.lua b/runtime/pb/json.lua
index 456266999c60d54f08baf1dc30fdaa907074184c..ca0931b8167de8da2a18ed4946bd301dd20f668e 100644
--- a/runtime/pb/json.lua
+++ b/runtime/pb/json.lua
@@ -364,7 +364,10 @@     if type(v) == 'string' then
         local n = enum_desc.by_name[v]
         if n ~= nil then return n end
     end
-    return tonumber(v) or v
+    -- proto3 JSON: unrecognized integer enum values pass through; unrecognized
+    -- string names yield nil so the caller can drop the element (repeated/map)
+    -- or fall back to the field default (singular).
+    return tonumber(v)
 end
 
 local function decode_field_value(field, v)
@@ -518,15 +521,23 @@         if f ~= nil then
             if f.kind == 'map' then
                 local m = {}
                 for mk, mv in pairs(jv) do
-                    m[decode_map_key(f.key, mk)] = decode_field_value(f.value, mv)
+                    local dv = decode_field_value(f.value, mv)
+                    if dv ~= nil then
+                        m[decode_map_key(f.key, mk)] = dv
+                    end
                 end
                 out[f.name] = m
             elseif f.repeated then
                 local arr = {}
-                for i = 1, #jv do arr[i] = decode_field_value(f, jv[i]) end
+                local n = 0
+                for i = 1, #jv do
+                    local dv = decode_field_value(f, jv[i])
+                    if dv ~= nil then n = n + 1; arr[n] = dv end
+                end
                 out[f.name] = arr
             else
-                out[f.name] = decode_field_value(f, jv)
+                local dv = decode_field_value(f, jv)
+                if dv ~= nil then out[f.name] = dv end
             end
         end
         -- Unknown JSON keys are silently ignored (per spec).
diff --git a/test/conformance/known_failures.txt b/test/conformance/known_failures.txt
index 81377d55fb2bbe3be55c10d6378407101e1034e4..c97776fcf23eb0cce2a3798e736fe0aeb963899b 100644
--- a/test/conformance/known_failures.txt
+++ b/test/conformance/known_failures.txt
@@ -19,11 +19,6 @@ #     because of the global JSON-output skip.
 #
 # Re-generate this file after fixes via `just conformance-refresh-failures`.
 Recommended.Proto3.JsonInput.FieldNameWithDoubleUnderscores.ProtobufOutput
-Recommended.Proto3.JsonInput.IgnoreUnknownEnumStringValueInMapPart.ProtobufOutput
-Recommended.Proto3.JsonInput.IgnoreUnknownEnumStringValueInMapValue.ProtobufOutput
-Recommended.Proto3.JsonInput.IgnoreUnknownEnumStringValueInOptionalField.ProtobufOutput
-Recommended.Proto3.JsonInput.IgnoreUnknownEnumStringValueInRepeatedField.ProtobufOutput
-Recommended.Proto3.JsonInput.IgnoreUnknownEnumStringValueInRepeatedPart.ProtobufOutput
 Recommended.Proto3.JsonInput.NullValueInOtherOneofOldFormat.Validator
 Recommended.Proto3.ProtobufInput.RejectInvalidUtf8.String.MapKey
 Recommended.Proto3.ProtobufInput.RejectInvalidUtf8.String.MapValue