diff --git a/src/qweb/expression_parser.ts b/src/qweb/expression_parser.ts
index 32a7a966..f0d8952d 100644
--- a/src/qweb/expression_parser.ts
+++ b/src/qweb/expression_parser.ts
@@ -81,7 +81,7 @@ const STATIC_TOKEN_MAP: { [key: string]: TKind } = {
 
 // note that the space after typeof is relevant. It makes sure that the formatted
 // expression has a space after typeof
-const OPERATORS = "...,.,===,==,+,!==,!=,!,||,&&,>=,>,<=,<,?,-,*,/,%,typeof ,=>,=,;".split(",");
+const OPERATORS = "...,.,===,==,+,!==,!=,!,||,&&,>=,>,<=,<,?,-,*,/,%,typeof ,=>,=,;,in ".split(",");
 
 type Tokenizer = (expr: string) => Token | false;
 
diff --git a/tests/qweb/qweb_expressions.test.ts b/tests/qweb/qweb_expressions.test.ts
index 9c6f8b6a..e713511c 100644
--- a/tests/qweb/qweb_expressions.test.ts
+++ b/tests/qweb/qweb_expressions.test.ts
@@ -56,6 +56,12 @@ describe("tokenizer", () => {
       { type: "OPERATOR", value: "..." },
       { type: "VALUE", value: "1" }
     ]);
+
+    expect(tokenize("a in b")).toEqual([
+      { type: "SYMBOL", value: "a" },
+      { type: "OPERATOR", value: "in " },
+      { type: "SYMBOL", value: "b" }
+    ]);
   });
 
   test("strings", () => {
@@ -134,6 +140,7 @@ describe("expression evaluation", () => {
     expect(compileExpr("color === 'black'", {})).toBe("scope['color']==='black'");
     expect(compileExpr("'li_'+item", {})).toBe("'li_'+scope['item']");
     expect(compileExpr("state.val > 1", {})).toBe("scope['state'].val>1");
+    expect(compileExpr("a in b", {})).toBe("scope['a']in scope['b']");
   });
 
   test("boolean operations", () => {