diff --git a/integration/map-bigint-optional/test.ts b/integration/map-bigint-optional/test.ts
index 19f092464..8abf1023a 100644
--- a/integration/map-bigint-optional/test.ts
+++ b/integration/map-bigint-optional/test.ts
@@ -124,15 +124,15 @@ export const MapBigInt = {
 };
 
 function createBaseMapBigInt_MapEntry(): MapBigInt_MapEntry {
-  return { key: BigInt("0"), value: BigInt("0") };
+  return { key: 0n, value: 0n };
 }
 
 export const MapBigInt_MapEntry = {
   encode(message: MapBigInt_MapEntry, writer: _m0.Writer = _m0.Writer.create()): _m0.Writer {
-    if (message.key !== BigInt("0")) {
+    if (message.key !== 0n) {
       writer.uint32(9).fixed64(message.key.toString());
     }
-    if (message.value !== BigInt("0")) {
+    if (message.value !== 0n) {
       writer.uint32(16).int64(message.value.toString());
     }
     if (message._unknownFields !== undefined) {
@@ -196,18 +196,15 @@ export const MapBigInt_MapEntry = {
   },
 
   fromJSON(object: any): MapBigInt_MapEntry {
-    return {
-      key: isSet(object.key) ? BigInt(object.key) : BigInt("0"),
-      value: isSet(object.value) ? BigInt(object.value) : BigInt("0"),
-    };
+    return { key: isSet(object.key) ? BigInt(object.key) : 0n, value: isSet(object.value) ? BigInt(object.value) : 0n };
   },
 
   toJSON(message: MapBigInt_MapEntry): unknown {
     const obj: any = {};
-    if (message.key !== BigInt("0")) {
+    if (message.key !== 0n) {
       obj.key = message.key.toString();
     }
-    if (message.value !== BigInt("0")) {
+    if (message.value !== 0n) {
       obj.value = message.value.toString();
     }
     return obj;
@@ -218,8 +215,8 @@ export const MapBigInt_MapEntry = {
   },
   fromPartial<I extends Exact<DeepPartial<MapBigInt_MapEntry>, I>>(object: I): MapBigInt_MapEntry {
     const message = createBaseMapBigInt_MapEntry();
-    message.key = object.key ?? BigInt("0");
-    message.value = object.value ?? BigInt("0");
+    message.key = object.key ?? 0n;
+    message.value = object.value ?? 0n;
     return message;
   },
 };
diff --git a/integration/simple-long-bigint/google/protobuf/timestamp.ts b/integration/simple-long-bigint/google/protobuf/timestamp.ts
index 6fbfc8858..0795c0425 100644
--- a/integration/simple-long-bigint/google/protobuf/timestamp.ts
+++ b/integration/simple-long-bigint/google/protobuf/timestamp.ts
@@ -112,12 +112,12 @@ export interface Timestamp {
 }
 
 function createBaseTimestamp(): Timestamp {
-  return { seconds: BigInt("0"), nanos: 0 };
+  return { seconds: 0n, nanos: 0 };
 }
 
 export const Timestamp = {
   encode(message: Timestamp, writer: _m0.Writer = _m0.Writer.create()): _m0.Writer {
-    if (message.seconds !== BigInt("0")) {
+    if (message.seconds !== 0n) {
       writer.uint32(8).int64(message.seconds.toString());
     }
     if (message.nanos !== 0) {
@@ -158,14 +158,14 @@ export const Timestamp = {
 
   fromJSON(object: any): Timestamp {
     return {
-      seconds: isSet(object.seconds) ? BigInt(object.seconds) : BigInt("0"),
+      seconds: isSet(object.seconds) ? BigInt(object.seconds) : 0n,
       nanos: isSet(object.nanos) ? Number(object.nanos) : 0,
     };
   },
 
   toJSON(message: Timestamp): unknown {
     const obj: any = {};
-    if (message.seconds !== BigInt("0")) {
+    if (message.seconds !== 0n) {
       obj.seconds = message.seconds.toString();
     }
     if (message.nanos !== 0) {
@@ -179,7 +179,7 @@ export const Timestamp = {
   },
   fromPartial<I extends Exact<DeepPartial<Timestamp>, I>>(object: I): Timestamp {
     const message = createBaseTimestamp();
-    message.seconds = object.seconds ?? BigInt("0");
+    message.seconds = object.seconds ?? 0n;
     message.nanos = object.nanos ?? 0;
     return message;
   },
diff --git a/integration/simple-long-bigint/google/protobuf/wrappers.ts b/integration/simple-long-bigint/google/protobuf/wrappers.ts
index ddfc5c942..fd1578038 100644
--- a/integration/simple-long-bigint/google/protobuf/wrappers.ts
+++ b/integration/simple-long-bigint/google/protobuf/wrappers.ts
@@ -209,12 +209,12 @@ export const FloatValue = {
 };
 
 function createBaseInt64Value(): Int64Value {
-  return { value: BigInt("0") };
+  return { value: 0n };
 }
 
 export const Int64Value = {
   encode(message: Int64Value, writer: _m0.Writer = _m0.Writer.create()): _m0.Writer {
-    if (message.value !== BigInt("0")) {
+    if (message.value !== 0n) {
       writer.uint32(8).int64(message.value.toString());
     }
     return writer;
@@ -244,12 +244,12 @@ export const Int64Value = {
   },
 
   fromJSON(object: any): Int64Value {
-    return { value: isSet(object.value) ? BigInt(object.value) : BigInt("0") };
+    return { value: isSet(object.value) ? BigInt(object.value) : 0n };
   },
 
   toJSON(message: Int64Value): unknown {
     const obj: any = {};
-    if (message.value !== BigInt("0")) {
+    if (message.value !== 0n) {
       obj.value = message.value.toString();
     }
     return obj;
@@ -260,18 +260,18 @@ export const Int64Value = {
   },
   fromPartial<I extends Exact<DeepPartial<Int64Value>, I>>(object: I): Int64Value {
     const message = createBaseInt64Value();
-    message.value = object.value ?? BigInt("0");
+    message.value = object.value ?? 0n;
     return message;
   },
 };
 
 function createBaseUInt64Value(): UInt64Value {
-  return { value: BigInt("0") };
+  return { value: 0n };
 }
 
 export const UInt64Value = {
   encode(message: UInt64Value, writer: _m0.Writer = _m0.Writer.create()): _m0.Writer {
-    if (message.value !== BigInt("0")) {
+    if (message.value !== 0n) {
       writer.uint32(8).uint64(message.value.toString());
     }
     return writer;
@@ -301,12 +301,12 @@ export const UInt64Value = {
   },
 
   fromJSON(object: any): UInt64Value {
-    return { value: isSet(object.value) ? BigInt(object.value) : BigInt("0") };
+    return { value: isSet(object.value) ? BigInt(object.value) : 0n };
   },
 
   toJSON(message: UInt64Value): unknown {
     const obj: any = {};
-    if (message.value !== BigInt("0")) {
+    if (message.value !== 0n) {
       obj.value = message.value.toString();
     }
     return obj;
@@ -317,7 +317,7 @@ export const UInt64Value = {
   },
   fromPartial<I extends Exact<DeepPartial<UInt64Value>, I>>(object: I): UInt64Value {
     const message = createBaseUInt64Value();
-    message.value = object.value ?? BigInt("0");
+    message.value = object.value ?? 0n;
     return message;
   },
 };
diff --git a/integration/simple-long-bigint/simple.ts b/integration/simple-long-bigint/simple.ts
index 5a3b26970..f5c592f3e 100644
--- a/integration/simple-long-bigint/simple.ts
+++ b/integration/simple-long-bigint/simple.ts
@@ -29,15 +29,15 @@ function createBaseNumbers(): Numbers {
     double: 0,
     float: 0,
     int32: 0,
-    int64: BigInt("0"),
+    int64: 0n,
     uint32: 0,
-    uint64: BigInt("0"),
+    uint64: 0n,
     sint32: 0,
-    sint64: BigInt("0"),
+    sint64: 0n,
     fixed32: 0,
-    fixed64: BigInt("0"),
+    fixed64: 0n,
     sfixed32: 0,
-    sfixed64: BigInt("0"),
+    sfixed64: 0n,
     guint64: undefined,
     timestamp: undefined,
     uint64s: [],
@@ -55,31 +55,31 @@ export const Numbers = {
     if (message.int32 !== 0) {
       writer.uint32(24).int32(message.int32);
     }
-    if (message.int64 !== BigInt("0")) {
+    if (message.int64 !== 0n) {
       writer.uint32(32).int64(message.int64.toString());
     }
     if (message.uint32 !== 0) {
       writer.uint32(40).uint32(message.uint32);
     }
-    if (message.uint64 !== BigInt("0")) {
+    if (message.uint64 !== 0n) {
       writer.uint32(48).uint64(message.uint64.toString());
     }
     if (message.sint32 !== 0) {
       writer.uint32(56).sint32(message.sint32);
     }
-    if (message.sint64 !== BigInt("0")) {
+    if (message.sint64 !== 0n) {
       writer.uint32(64).sint64(message.sint64.toString());
     }
     if (message.fixed32 !== 0) {
       writer.uint32(77).fixed32(message.fixed32);
     }
-    if (message.fixed64 !== BigInt("0")) {
+    if (message.fixed64 !== 0n) {
       writer.uint32(81).fixed64(message.fixed64.toString());
     }
     if (message.sfixed32 !== 0) {
       writer.uint32(93).sfixed32(message.sfixed32);
     }
-    if (message.sfixed64 !== BigInt("0")) {
+    if (message.sfixed64 !== 0n) {
       writer.uint32(97).sfixed64(message.sfixed64.toString());
     }
     if (message.guint64 !== undefined) {
@@ -232,15 +232,15 @@ export const Numbers = {
       double: isSet(object.double) ? Number(object.double) : 0,
       float: isSet(object.float) ? Number(object.float) : 0,
       int32: isSet(object.int32) ? Number(object.int32) : 0,
-      int64: isSet(object.int64) ? BigInt(object.int64) : BigInt("0"),
+      int64: isSet(object.int64) ? BigInt(object.int64) : 0n,
       uint32: isSet(object.uint32) ? Number(object.uint32) : 0,
-      uint64: isSet(object.uint64) ? BigInt(object.uint64) : BigInt("0"),
+      uint64: isSet(object.uint64) ? BigInt(object.uint64) : 0n,
       sint32: isSet(object.sint32) ? Number(object.sint32) : 0,
-      sint64: isSet(object.sint64) ? BigInt(object.sint64) : BigInt("0"),
+      sint64: isSet(object.sint64) ? BigInt(object.sint64) : 0n,
       fixed32: isSet(object.fixed32) ? Number(object.fixed32) : 0,
-      fixed64: isSet(object.fixed64) ? BigInt(object.fixed64) : BigInt("0"),
+      fixed64: isSet(object.fixed64) ? BigInt(object.fixed64) : 0n,
       sfixed32: isSet(object.sfixed32) ? Number(object.sfixed32) : 0,
-      sfixed64: isSet(object.sfixed64) ? BigInt(object.sfixed64) : BigInt("0"),
+      sfixed64: isSet(object.sfixed64) ? BigInt(object.sfixed64) : 0n,
       guint64: isSet(object.guint64) ? BigInt(object.guint64) : undefined,
       timestamp: isSet(object.timestamp) ? fromJsonTimestamp(object.timestamp) : undefined,
       uint64s: globalThis.Array.isArray(object?.uint64s) ? object.uint64s.map((e: any) => BigInt(e)) : [],
@@ -258,31 +258,31 @@ export const Numbers = {
     if (message.int32 !== 0) {
       obj.int32 = Math.round(message.int32);
     }
-    if (message.int64 !== BigInt("0")) {
+    if (message.int64 !== 0n) {
       obj.int64 = message.int64.toString();
     }
     if (message.uint32 !== 0) {
       obj.uint32 = Math.round(message.uint32);
     }
-    if (message.uint64 !== BigInt("0")) {
+    if (message.uint64 !== 0n) {
       obj.uint64 = message.uint64.toString();
     }
     if (message.sint32 !== 0) {
       obj.sint32 = Math.round(message.sint32);
     }
-    if (message.sint64 !== BigInt("0")) {
+    if (message.sint64 !== 0n) {
       obj.sint64 = message.sint64.toString();
     }
     if (message.fixed32 !== 0) {
       obj.fixed32 = Math.round(message.fixed32);
     }
-    if (message.fixed64 !== BigInt("0")) {
+    if (message.fixed64 !== 0n) {
       obj.fixed64 = message.fixed64.toString();
     }
     if (message.sfixed32 !== 0) {
       obj.sfixed32 = Math.round(message.sfixed32);
     }
-    if (message.sfixed64 !== BigInt("0")) {
+    if (message.sfixed64 !== 0n) {
       obj.sfixed64 = message.sfixed64.toString();
     }
     if (message.guint64 !== undefined) {
@@ -305,15 +305,15 @@ export const Numbers = {
     message.double = object.double ?? 0;
     message.float = object.float ?? 0;
     message.int32 = object.int32 ?? 0;
-    message.int64 = object.int64 ?? BigInt("0");
+    message.int64 = object.int64 ?? 0n;
     message.uint32 = object.uint32 ?? 0;
-    message.uint64 = object.uint64 ?? BigInt("0");
+    message.uint64 = object.uint64 ?? 0n;
     message.sint32 = object.sint32 ?? 0;
-    message.sint64 = object.sint64 ?? BigInt("0");
+    message.sint64 = object.sint64 ?? 0n;
     message.fixed32 = object.fixed32 ?? 0;
-    message.fixed64 = object.fixed64 ?? BigInt("0");
+    message.fixed64 = object.fixed64 ?? 0n;
     message.sfixed32 = object.sfixed32 ?? 0;
-    message.sfixed64 = object.sfixed64 ?? BigInt("0");
+    message.sfixed64 = object.sfixed64 ?? 0n;
     message.guint64 = object.guint64 ?? undefined;
     message.timestamp = object.timestamp ?? undefined;
     message.uint64s = object.uint64s?.map((e) => e) || [];
diff --git a/src/types.ts b/src/types.ts
index d3722e75e..18e531779 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -209,7 +209,7 @@ export function defaultValue(ctx: Context, field: FieldDescriptorProto): any {
       } else if (options.forceLong === LongOption.STRING) {
         return '"0"';
       } else if (options.forceLong === LongOption.BIGINT) {
-        return 'BigInt("0")';
+        return '0n';
       } else {
         return 0;
       }
@@ -221,7 +221,7 @@ export function defaultValue(ctx: Context, field: FieldDescriptorProto): any {
       } else if (options.forceLong === LongOption.STRING) {
         return '"0"';
       } else if (options.forceLong === LongOption.BIGINT) {
-        return 'BigInt("0")';
+        return '0n';
       } else {
         return 0;
       }
@@ -286,7 +286,7 @@ export function notDefaultCheck(
       } else if (options.forceLong === LongOption.STRING) {
         return code`${maybeNotUndefinedAnd} ${place} !== "0"`;
       } else if (options.forceLong === LongOption.BIGINT) {
-        return code`${maybeNotUndefinedAnd} ${place} !== BigInt("0")`;
+        return code`${maybeNotUndefinedAnd} ${place} !== 0n`;
       } else {
         return code`${maybeNotUndefinedAnd} ${place} !== 0`;
       }