diff --git a/.gitignore b/.gitignore
index 5e4bc0af5ea..f1ea04e3efb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -41,6 +41,7 @@ tests/cases/**/*.js.map
 scripts/debug.bat
 scripts/run.bat
 scripts/word2md.js
+scripts/buildProtocol.js
 scripts/ior.js
 scripts/buildProtocol.js
 scripts/*.js.map
diff --git a/scripts/buildProtocol.ts b/scripts/buildProtocol.ts
index 8d49262a470..55ad086815c 100644
--- a/scripts/buildProtocol.ts
+++ b/scripts/buildProtocol.ts
@@ -42,7 +42,14 @@ class DeclarationsWalker {
                     return;
                 }
                 // splice declaration in final d.ts file
-                const text = decl.getFullText();
+                let text = decl.getFullText();
+                if (decl.kind === ts.SyntaxKind.EnumDeclaration && !(decl.flags & ts.NodeFlags.Const)) {
+                    // patch enum declaration to make them constan
+                    const declStart = decl.getStart() - decl.getFullStart();
+                    const prefix = text.substring(0, declStart);
+                    const suffix = text.substring(declStart + "enum".length, decl.getEnd() - decl.getFullStart());
+                    text = prefix + "const enum" + suffix;
+                }
                 this.text += `${text}\n`;
 
                 // recursively pull all dependencies into result dts file