diff --git a/js/src/gc/GCRuntime.h b/js/src/gc/GCRuntime.h
index 9b3436db34e..97a90ca8086 100644
--- a/js/src/gc/GCRuntime.h
+++ b/js/src/gc/GCRuntime.h
@@ -732,7 +732,7 @@ class GCRuntime
 
     void setMaxMallocBytes(size_t value);
     void resetMallocBytes();
-    bool isTooMuchMalloc() const { return mallocBytes <= 0; }
+    bool isTooMuchMalloc() const { return mallocBytesUntilGC <= 0; }
     void updateMallocCounter(JS::Zone *zone, size_t nbytes);
     void onTooMuchMalloc();
 
@@ -1178,11 +1178,11 @@ class GCRuntime
      * Malloc counter to measure memory pressure for GC scheduling. It runs
      * from maxMallocBytes down to zero.
      */
-    mozilla::Atomic<ptrdiff_t, mozilla::ReleaseAcquire> mallocBytes;
+    mozilla::Atomic<ptrdiff_t, mozilla::ReleaseAcquire> mallocBytesUntilGC;
 
     /*
-     * Whether a GC has been triggered as a result of mallocBytes falling
-     * below zero.
+     * Whether a GC has been triggered as a result of mallocBytesUntilGC
+     * falling below zero.
      */
     mozilla::Atomic<bool, mozilla::ReleaseAcquire> mallocGCTriggered;
 
diff --git a/js/src/jsgc.cpp b/js/src/jsgc.cpp
index 09c6d93a445..e9e2452166e 100644
--- a/js/src/jsgc.cpp
+++ b/js/src/jsgc.cpp
@@ -1127,7 +1127,7 @@ GCRuntime::GCRuntime(JSRuntime *rt) :
 #endif
     validate(true),
     fullCompartmentChecks(false),
-    mallocBytes(0),
+    mallocBytesUntilGC(0),
     mallocGCTriggered(false),
     alwaysPreserveCode(false),
 #ifdef DEBUG
@@ -1655,14 +1655,14 @@ GCRuntime::setMaxMallocBytes(size_t value)
 void
 GCRuntime::resetMallocBytes()
 {
-    mallocBytes = ptrdiff_t(maxMallocBytes);
+    mallocBytesUntilGC = ptrdiff_t(maxMallocBytes);
     mallocGCTriggered = false;
 }
 
 void
 GCRuntime::updateMallocCounter(JS::Zone *zone, size_t nbytes)
 {
-    mallocBytes -= ptrdiff_t(nbytes);
+    mallocBytesUntilGC -= ptrdiff_t(nbytes);
     if (MOZ_UNLIKELY(isTooMuchMalloc()))
         onTooMuchMalloc();
     else if (zone)