diff --git a/js/src/ion/IonBuilder.cpp b/js/src/ion/IonBuilder.cpp
index 0a8bee8db55c..fde1c30c04fa 100644
--- a/js/src/ion/IonBuilder.cpp
+++ b/js/src/ion/IonBuilder.cpp
@@ -2993,7 +2993,7 @@ IonBuilder::inlineScriptedCall(HandleFunction target, CallInfo &callInfo)
     LifoAlloc *alloc = GetIonContext()->temp->lifoAlloc();
     CompileInfo *info = alloc->new_<CompileInfo>(calleeScript.get(), target,
                                                  (jsbytecode *)NULL, thisCall.constructing(),
-                                                 SequentialExecution);
+                                                 this->info().executionMode());
     if (!info)
         return false;
 
diff --git a/js/src/ion/ParallelArrayAnalysis.cpp b/js/src/ion/ParallelArrayAnalysis.cpp
index 83cb6705551a..e16bf53965fa 100644
--- a/js/src/ion/ParallelArrayAnalysis.cpp
+++ b/js/src/ion/ParallelArrayAnalysis.cpp
@@ -529,7 +529,7 @@ ParallelArrayVisitor::convertToBailout(MBasicBlock *block, MInstruction *ins)
             continue;
 
         // create bailout block to insert on this edge
-        MBasicBlock *bailBlock = MBasicBlock::NewParBailout(graph_, block->info(), pred, pc);
+        MBasicBlock *bailBlock = MBasicBlock::NewParBailout(graph_, pred->info(), pred, pc);
         if (!bailBlock)
             return false;
 
diff --git a/js/src/jit-test/tests/parallelarray/bug854021.js b/js/src/jit-test/tests/parallelarray/bug854021.js
new file mode 100644
index 000000000000..a451e5413966
--- /dev/null
+++ b/js/src/jit-test/tests/parallelarray/bug854021.js
@@ -0,0 +1,2 @@
+// Don't crash.
+ParallelArray(7, function ([y]) {})