diff --git a/doc/component.md b/doc/component.md
index a84eca5b..a2c70bb7 100644
--- a/doc/component.md
+++ b/doc/component.md
@@ -379,7 +379,7 @@ The `t-widget` directive also accepts dynamic values with string interpolation
 
 ```xml
 <div t-name="ParentWidget">
-    <t t-widget="ChildWidget#{id}"/>
+    <t t-widget="ChildWidget{{id}}"/>
 </div>
 ```
 
@@ -390,14 +390,6 @@ class ParentWidget {
 }
 ```
 
-Similarly to `t-attf-`, there is an alternate form of string interpolation:
-
-```xml
-<div t-name="ParentWidget">
-    <t t-widget="ChildWidget{{id}}"/>
-</div>
-```
-
 **CSS and style:** there is some specific support to allow the parent to declare
 additional css classes or style for the sub widget: css declared in `class`, `style`, `t-att-class` or `t-att-style` will be added to the
 root widget element.
@@ -754,20 +746,13 @@ The `t-ref` directive also accepts dynamic values with string interpolation
 `id` set to 44 in the rendering context,
 
 ```xml
-<div t-ref="widget_#{id}"/>
+<div t-ref="widget_{{id}}"/>
 ```
 
 ```js
 this.refs.widget_44;
 ```
 
-Similarly to `t-attf-` and `t-widget`, there is an alternate form of string
-interpolation:
-
-```xml
-<div t-ref="widget_{{id}}"/>
-```
-
 ### Asynchronous rendering
 
 Working with asynchronous code always adds a lot of complexity to a system. Whenever
diff --git a/doc/qweb.md b/doc/qweb.md
index 4feb0354..80dbf582 100644
--- a/doc/qweb.md
+++ b/doc/qweb.md
@@ -357,13 +357,6 @@ If an expression evaluates to a falsy value, it will not be set at all:
 There is another way to format a string attribute: the `t-attf-` directive. With
 it, you get string interpolation:
 
-```xml
-<div t-attf-foo="a #{value1} is #{value2} of #{value3} ]"/>
-<!-- result if values are set to 1,2 and 3: <div foo="a 0 is 1 of 2 ]"></div> -->
-```
-
-For historical reason, there is an alternate form of string interpolation:
-
 ```xml
 <div t-attf-foo="a {{value1}} is {{value2}} of {{value3}} ]"/>
 <!-- result if values are set to 1,2 and 3: <div foo="a 0 is 1 of 2 ]"></div> -->
diff --git a/src/qweb_core.ts b/src/qweb_core.ts
index 563844d7..5abaf5d9 100644
--- a/src/qweb_core.ts
+++ b/src/qweb_core.ts
@@ -777,15 +777,11 @@ export class Context {
     if (matches && matches[0].length === s.length) {
       return `(${this.formatExpression(s.slice(2, -2))})`;
     }
-    matches = s.match(/\#\{.*?\}/g);
-    if (matches && matches[0].length === s.length) {
-      return `(${this.formatExpression(s.slice(2, -1))})`;
-    }
 
-    let formatter = expr => "${" + this.formatExpression(expr) + "}";
-    let r = s
-      .replace(/\{\{.*?\}\}/g, s => formatter(s.slice(2, -2)))
-      .replace(/\#\{.*?\}/g, s => formatter(s.slice(2, -1)));
+    let r = s.replace(
+      /\{\{.*?\}\}/g,
+      s => "${" + this.formatExpression(s.slice(2, -2)) + "}"
+    );
     return "`" + r + "`";
   }
 }
diff --git a/tests/qweb.test.ts b/tests/qweb.test.ts
index c2d5b32a..9763c176 100644
--- a/tests/qweb.test.ts
+++ b/tests/qweb.test.ts
@@ -485,7 +485,7 @@ describe("attributes", () => {
   });
 
   test("format expression, other format", () => {
-    qweb.addTemplate("test", `<div t-attf-foo="#{value + 37}"/>`);
+    qweb.addTemplate("test", `<div t-attf-foo="{{value + 37}}"/>`);
     const result = renderToString(qweb, "test", { value: 5 });
     expect(result).toBe(`<div foo="42"></div>`);
   });
@@ -530,7 +530,7 @@ describe("attributes", () => {
   });
 
   test("class and t-attf-class with ternary operation", () => {
-    qweb.addTemplate("test", `<div class="hello" t-attf-class="#{value ? 'world' : ''}"/>`);
+    qweb.addTemplate("test", `<div class="hello" t-attf-class="{{value ? 'world' : ''}}"/>`);
     const result = renderToString(qweb, "test", { value: true });
     expect(result).toBe(`<div class="hello world"></div>`);
   });