diff --git a/js/src/frontend/Parser.cpp b/js/src/frontend/Parser.cpp
index c1db6ef8ab2..d0604aaab8f 100644
--- a/js/src/frontend/Parser.cpp
+++ b/js/src/frontend/Parser.cpp
@@ -2990,7 +2990,7 @@ Parser::forStatement()
 
     pn->setOp(JSOP_ITER);
     pn->pn_iflags = 0;
-    if (tokenStream.matchToken(TOK_NAME)) {
+    if (allowsForEachIn() && tokenStream.matchToken(TOK_NAME)) {
         if (tokenStream.currentToken().name() == context->names().each)
             pn->pn_iflags = JSITER_FOREACH;
         else
@@ -5119,7 +5119,7 @@ Parser::comprehensionTail(ParseNode *kid, unsigned blockid, bool isGenexp,
 
         pn2->setOp(JSOP_ITER);
         pn2->pn_iflags = JSITER_ENUMERATE;
-        if (tokenStream.matchToken(TOK_NAME)) {
+        if (allowsForEachIn() && tokenStream.matchToken(TOK_NAME)) {
             if (tokenStream.currentToken().name() == context->names().each)
                 pn2->pn_iflags |= JSITER_FOREACH;
             else
diff --git a/js/src/frontend/Parser.h b/js/src/frontend/Parser.h
index f052304cfdf..510adfb697f 100644
--- a/js/src/frontend/Parser.h
+++ b/js/src/frontend/Parser.h
@@ -468,6 +468,16 @@ struct Parser : private AutoGCRooter
     ParseNode *propertyQualifiedIdentifier();
 #endif /* JS_HAS_XML_SUPPORT */
 
+    bool allowsForEachIn() {
+#if !JS_HAS_FOR_EACH_IN
+        return false;
+#elif JS_HAS_XML_SUPPORT
+        return allowsXML() || tokenStream.hasMoarXML();
+#else
+        return versionNumber() >= JSVERSION_1_6;
+#endif
+    }
+
     bool setAssignmentLhsOps(ParseNode *pn, JSOp op);
     bool matchInOrOf(bool *isForOfp);
 };
diff --git a/js/src/jsversion.h b/js/src/jsversion.h
index 475525177a6..50e2fa6beb0 100644
--- a/js/src/jsversion.h
+++ b/js/src/jsversion.h
@@ -61,6 +61,7 @@
 #define JS_HAS_CONST            0       /* has JS2 const as alternative var */
 #define JS_HAS_FUN_EXPR_STMT    0       /* has function expression statement */
 #define JS_HAS_NO_SUCH_METHOD   0       /* has o.__noSuchMethod__ handler */
+#define JS_HAS_FOR_EACH_IN      0       /* has for each (lhs in iterable) */
 #define JS_HAS_GENERATORS       0       /* has yield in generator function */
 #define JS_HAS_BLOCK_SCOPE      0       /* has block scope via let/arraycomp */
 #define JS_HAS_DESTRUCTURING    0       /* has [a,b] = ... or {p:a,q:b} = ... */
@@ -82,6 +83,7 @@
 #define JS_HAS_CONST            1       /* has JS2 const as alternative var */
 #define JS_HAS_FUN_EXPR_STMT    1       /* has function expression statement */
 #define JS_HAS_NO_SUCH_METHOD   1       /* has o.__noSuchMethod__ handler */
+#define JS_HAS_FOR_EACH_IN      0       /* has for each (lhs in iterable) */
 #define JS_HAS_GENERATORS       0       /* has yield in generator function */
 #define JS_HAS_BLOCK_SCOPE      0       /* has block scope via let/arraycomp */
 #define JS_HAS_DESTRUCTURING    0       /* has [a,b] = ... or {p:a,q:b} = ... */
@@ -99,6 +101,7 @@
 #define JS_HAS_CONST            1       /* has JS2 const as alternative var */
 #define JS_HAS_FUN_EXPR_STMT    1       /* has function expression statement */
 #define JS_HAS_NO_SUCH_METHOD   1       /* has o.__noSuchMethod__ handler */
+#define JS_HAS_FOR_EACH_IN      1       /* has for each (lhs in iterable) */
 #define JS_HAS_GENERATORS       0       /* has yield in generator function */
 #define JS_HAS_BLOCK_SCOPE      0       /* has block scope via let/arraycomp */
 #define JS_HAS_DESTRUCTURING    0       /* has [a,b] = ... or {p:a,q:b} = ... */
@@ -116,6 +119,7 @@
 #define JS_HAS_CONST            1       /* has JS2 const as alternative var */
 #define JS_HAS_FUN_EXPR_STMT    1       /* has function expression statement */
 #define JS_HAS_NO_SUCH_METHOD   1       /* has o.__noSuchMethod__ handler */
+#define JS_HAS_FOR_EACH_IN      1       /* has for each (lhs in iterable) */
 #define JS_HAS_GENERATORS       1       /* has yield in generator function */
 #define JS_HAS_BLOCK_SCOPE      1       /* has block scope via let/arraycomp */
 #define JS_HAS_DESTRUCTURING    1       /* has [a,b] = ... or {p:a,q:b} = ... */
@@ -133,6 +137,7 @@
 #define JS_HAS_CONST            1       /* has JS2 const as alternative var */
 #define JS_HAS_FUN_EXPR_STMT    1       /* has function expression statement */
 #define JS_HAS_NO_SUCH_METHOD   1       /* has o.__noSuchMethod__ handler */
+#define JS_HAS_FOR_EACH_IN      1       /* has for each (lhs in iterable) */
 #define JS_HAS_GENERATORS       1       /* has yield in generator function */
 #define JS_HAS_BLOCK_SCOPE      1       /* has block scope via let/arraycomp */
 #define JS_HAS_DESTRUCTURING    2       /* has [a,b] = ... or {p:a,q:b} = ... */