diff --git a/src/qweb/expression_parser.ts b/src/qweb/expression_parser.ts
index 95da771e..3d11294b 100644
--- a/src/qweb/expression_parser.ts
+++ b/src/qweb/expression_parser.ts
@@ -29,14 +29,14 @@ const RESERVED_WORDS = "true,false,NaN,null,undefined,debugger,console,window,in
   ","
 );
 
-const WORD_REPLACEMENT = {
+const WORD_REPLACEMENT = Object.assign(Object.create(null), {
   and: "&&",
   or: "||",
   gt: ">",
   gte: ">=",
   lt: "<",
   lte: "<=",
-};
+});
 
 export interface QWebVar {
   id: string; // foo
@@ -69,7 +69,7 @@ interface Token {
   varName?: string;
 }
 
-const STATIC_TOKEN_MAP: { [key: string]: TKind } = {
+const STATIC_TOKEN_MAP: { [key: string]: TKind } = Object.assign(Object.create(null), {
   "{": "LEFT_BRACE",
   "}": "RIGHT_BRACE",
   "[": "LEFT_BRACKET",
@@ -78,7 +78,7 @@ const STATIC_TOKEN_MAP: { [key: string]: TKind } = {
   ",": "COMMA",
   "(": "LEFT_PAREN",
   ")": "RIGHT_PAREN",
-};
+});
 
 // note that the space after typeof is relevant. It makes sure that the formatted
 // expression has a space after typeof
diff --git a/tests/qweb/qweb_expressions.test.ts b/tests/qweb/qweb_expressions.test.ts
index de4f383d..226c9b76 100644
--- a/tests/qweb/qweb_expressions.test.ts
+++ b/tests/qweb/qweb_expressions.test.ts
@@ -196,4 +196,8 @@ describe("expression evaluation", () => {
     expect(compileExpr("f(...state.list)", {})).toBe("scope['f'](...scope['state'].list)");
     expect(compileExpr("f([...list])", {})).toBe("scope['f']([...scope['list']])");
   });
+
+  test("works with builtin properties", () => {
+    expect(compileExpr("state.constructor.name", {})).toBe("scope['state'].constructor.name");
+  });
 });