diff --git a/dlls/jscript/engine.c b/dlls/jscript/engine.c
index 5f93ace2ada..2b9a2bb2a53 100644
--- a/dlls/jscript/engine.c
+++ b/dlls/jscript/engine.c
@@ -2870,10 +2870,14 @@ HRESULT assign_expression_eval(exec_ctx_t *ctx, expression_t *_expr, DWORD flags
     return S_OK;
 }
 
-HRESULT assign_lshift_expression_eval(exec_ctx_t *ctx, expression_t *expr, DWORD flags, jsexcept_t *ei, exprval_t *ret)
+/* ECMA-262 3rd Edition    11.13.2 */
+HRESULT assign_lshift_expression_eval(exec_ctx_t *ctx, expression_t *_expr, DWORD flags, jsexcept_t *ei, exprval_t *ret)
 {
-    FIXME("\n");
-    return E_NOTIMPL;
+    binary_expression_t *expr = (binary_expression_t*)_expr;
+
+    TRACE("\n");
+
+    return assign_oper_eval(ctx, expr->expression1, expr->expression2, lshift_eval, ei, ret);
 }
 
 HRESULT assign_rshift_expression_eval(exec_ctx_t *ctx, expression_t *expr, DWORD flags, jsexcept_t *ei, exprval_t *ret)
diff --git a/dlls/jscript/tests/lang.js b/dlls/jscript/tests/lang.js
index 45bdd4e58d0..5e725be91c9 100644
--- a/dlls/jscript/tests/lang.js
+++ b/dlls/jscript/tests/lang.js
@@ -246,6 +246,9 @@ tmp = 5;
 ok((tmp /= 2) === 2.5, "tmp /= 2 !== 2.5");
 ok(tmp === 2.5, "tmp !=== 2.5");
 
+tmp = 8;
+ok((tmp <<= 1) === 16, "tmp <<= 1 !== 16");
+
 tmp = 3 || ok(false, "second or expression called");
 ok(tmp === 3, "3 || (...) is not 3");