diff --git a/packages/protobuf-test/src/json.test.ts b/packages/protobuf-test/src/json.test.ts
index e0692cd90..f6e977410 100644
--- a/packages/protobuf-test/src/json.test.ts
+++ b/packages/protobuf-test/src/json.test.ts
@@ -455,6 +455,26 @@ describe("JSON serialization", () => {
       });
     });
     testJson(TimestampSchema, {}, "1970-01-01T00:00:00Z");
+    test(`fromJson decodes ${TimestampSchema.typeName}`, () => {
+      const decode = (str: string, seconds: number, nanos: number) =>
+        expect(fromJson(TimestampSchema, str)).toStrictEqual({
+          $typeName: "google.protobuf.Timestamp",
+          seconds: protoInt64.parse(seconds),
+          nanos,
+        });
+
+      decode("2025-01-27T11:42:15.689823456+01:00", 1737974535, 689823456);
+      decode("2025-01-27T11:42:15.6898+01:00", 1737974535, 689800000);
+      decode("2025-01-27T11:42:15.6+01:00", 1737974535, 600000000);
+      decode("2025-01-27T11:42:15.0+01:00", 1737974535, 0);
+      decode("2025-01-27T11:42:15+01:00", 1737974535, 0);
+      decode("2025-01-27T11:42:15.689823456Z", 1737978135, 689823456);
+      decode("2025-01-27T11:42:15.689800Z", 1737978135, 689800000);
+      decode("2025-01-27T11:42:15.6898Z", 1737978135, 689800000);
+      decode("2025-01-27T11:42:15.6Z", 1737978135, 600000000);
+      decode("2025-01-27T11:42:15.0Z", 1737978135, 0);
+      decode("2025-01-27T11:42:15Z", 1737978135, 0);
+    });
     describe("FieldMask", () => {
       testJson(
         FieldMaskSchema,
diff --git a/packages/protobuf/src/from-json.ts b/packages/protobuf/src/from-json.ts
index d2dac8339..0e896109a 100644
--- a/packages/protobuf/src/from-json.ts
+++ b/packages/protobuf/src/from-json.ts
@@ -718,7 +718,7 @@ function timestampFromJson(timestamp: Timestamp, json: JsonValue) {
     );
   }
   const matches = json.match(
-    /^([0-9]{4})-([0-9]{2})-([0-9]{2})T([0-9]{2}):([0-9]{2}):([0-9]{2})(?:Z|\.([0-9]{3,9})Z|([+-][0-9][0-9]:[0-9][0-9]))$/,
+    /^([0-9]{4})-([0-9]{2})-([0-9]{2})T([0-9]{2}):([0-9]{2}):([0-9]{2})(?:\.([0-9]{1,9}))?(?:Z|([+-][0-9][0-9]:[0-9][0-9]))$/,
   );
   if (!matches) {
     throw new Error(