--- a/js/src/asmjs/AsmJSValidate.cpp
+++ b/js/src/asmjs/AsmJSValidate.cpp
@@ -6848,21 +6848,25 @@ ParseFunction(ModuleCompiler &m, ParseNo
 
     Directives newDirectives = directives;
     AsmJSParseContext funpc(&m.parser(), outerpc, fn, funbox, &newDirectives,
                             outerpc->staticLevel + 1, outerpc->blockidGen,
                             /* blockScopeDepth = */ 0);
     if (!funpc.init(tokenStream))
         return false;
 
-    if (!m.parser().functionArgsAndBodyGeneric(fn, fun, Normal, Statement))
-        return false;
-
-    if (tokenStream.hadError() || directives != newDirectives)
-        return false;
+    if (!m.parser().functionArgsAndBodyGeneric(fn, fun, Normal, Statement)) {
+        if (tokenStream.hadError() || directives == newDirectives)
+            return false;
+
+        return m.fail(nullptr, "encountered new directive");
+    }
+
+    MOZ_ASSERT(!tokenStream.hadError());
+    MOZ_ASSERT(directives == newDirectives);
 
     outerpc->blockidGen = funpc.blockidGen;
     fn->pn_blockid = outerpc->blockid();
 
     *fnOut = fn;
     return true;
 }
 

--- a/js/src/jit-test/tests/asm.js/testBasic.js
+++ b/js/src/jit-test/tests/asm.js/testBasic.js
@@ -14,16 +14,17 @@ assertAsmTypeFail(USE_ASM + 'var f = f;'
 assertAsmTypeFail(USE_ASM + 'var f=0; function f(){} return f');
 assertAsmTypeFail(USE_ASM + 'var f=glob.Math.imul; return {}');
 assertAsmTypeFail('glob', USE_ASM + 'var f=glob.Math.imul; function f(){} return f');
 assertAsmTypeFail('glob','foreign', USE_ASM + 'var f=foreign.foo; function f(){} return f');
 assertAsmTypeFail(USE_ASM + 'function f(){} var f=[f,f]; return f');
 assertAsmTypeFail(USE_ASM + 'function f() 0; return f');
 assertAsmTypeFail('"use strict";' + USE_ASM + 'function f() {} return f');
 assertAsmTypeFail(USE_ASM + '"use strict"; function f() {} return f');
+assertAsmTypeFail(USE_ASM + 'function f() { "use strict"; } return f');
 assertEq(asmLink(asmCompile(USE_ASM + 'function f(){} return f'))(), undefined);
 assertEq(asmLink(asmCompile(USE_ASM + 'function f(){;} return f'))(), undefined);
 assertAsmTypeFail(USE_ASM + 'function f(i,j){;} return f');
 assertEq(asmLink(asmCompile('"use asm";; function f(){};;; return f;;'))(), undefined);
 assertAsmTypeFail(USE_ASM + 'function f(x){} return f');
 assertAsmTypeFail(USE_ASM + 'function f(){return; return 1} return f');
 assertEq(asmLink(asmCompile(USE_ASM + 'function f(x){x=x|0} return f'))(42), undefined);
 assertEq(asmLink(asmCompile(USE_ASM + 'function f(x){x=x|0; return x|0} return f'))(42), 42);