diff --git a/src/ts/enum.ts b/src/ts/enum.ts
index f1a44fea..83e7f11f 100644
--- a/src/ts/enum.ts
+++ b/src/ts/enum.ts
@@ -6,7 +6,7 @@ export function printEnum(enumDescriptor: EnumDescriptorProto, indentLevel: numb
   printer.printEmptyLn();
   printer.printLn(`export enum ${enumDescriptor.getName()} {`);
   enumDescriptor.getValueList().forEach(value => {
-    printer.printIndentedLn(`${value.getName()} = ${value.getNumber()},`);
+    printer.printIndentedLn(`${value.getName().toUpperCase()} = ${value.getNumber()},`);
   });
   printer.printLn(`}`);
   return printer.getOutput();
diff --git a/test/proto/examplecom/enum_message.proto b/test/proto/examplecom/enum_message.proto
index 92bf5a1e..db11f682 100644
--- a/test/proto/examplecom/enum_message.proto
+++ b/test/proto/examplecom/enum_message.proto
@@ -9,6 +9,7 @@ message EnumMessage {
         DEFAULT = 0;
         FIRST = 1;
         SECOND = 2;
+        Third = 3;  // protoc will convert to ALL_CAPS.
     }
 
     InternalEnum internal_enum = 1;
diff --git a/test/ts_test/src/enums.ts b/test/ts_test/src/enums.ts
index 7204d4dc..56cc8d70 100644
--- a/test/ts_test/src/enums.ts
+++ b/test/ts_test/src/enums.ts
@@ -42,3 +42,11 @@ describe("external enums", () => {
     assert.deepEqual(parentMsg.getExternalEnumsList(), [ExternalEnum.FIRST, ExternalEnum.SECOND]);
   });
 });
+
+describe("enum casing", () => {
+  it("should export enums as ALL_CAPS in proto definitions (#21)", () => {
+    const parentMsg = new EnumMessage();
+    parentMsg.setInternalEnum(InternalEnum.THIRD); // should compile.
+    assert.ok(true, ".d.ts file should export the enum definition in ALL_CAPS");
+  });
+});
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