diff --git a/toolkit/components/aboutmemory/tests/test_aboutmemory5.xul b/toolkit/components/aboutmemory/tests/test_aboutmemory5.xul
index 50a464310cce..9aa61e290a66 100644
--- a/toolkit/components/aboutmemory/tests/test_aboutmemory5.xul
+++ b/toolkit/components/aboutmemory/tests/test_aboutmemory5.xul
@@ -104,7 +104,8 @@
         // If we have more than 1000 chars, we've probably successfully
         // copy+pasted.
         if (actual.length > 1000) {
-          let vsizes = actual.match(/vsize/g);
+          // Note: Match "vsize" but not "vsize-max-contiguous".
+          let vsizes = actual.match(/vsize[^-]/g);
           let endOfBrowsers  = actual.match(/End of Browser/g);
 
           if (vsizes.length == 4 && endOfBrowsers.length == 3) {
diff --git a/xpcom/base/nsMemoryReporterManager.cpp b/xpcom/base/nsMemoryReporterManager.cpp
index 2253d32983d2..a6594960fa33 100644
--- a/xpcom/base/nsMemoryReporterManager.cpp
+++ b/xpcom/base/nsMemoryReporterManager.cpp
@@ -400,6 +400,20 @@ static nsresult GetVsizeMaxContiguous(int64_t* aN)
     return NS_OK;
 }
 
+class VsizeMaxContiguousReporter MOZ_FINAL : public MemoryUniReporter
+{
+public:
+    VsizeMaxContiguousReporter()
+      : MemoryUniReporter("vsize-max-contiguous", KIND_OTHER, UNITS_BYTES,
+"Size of the maximum contiguous block of available virtual memory.")
+    {}
+
+    NS_IMETHOD GetAmount(int64_t* aAmount)
+    {
+        return GetVsizeMaxContiguous(aAmount);
+    }
+};
+
 #define HAVE_PRIVATE_REPORTER
 class PrivateReporter MOZ_FINAL : public MemoryUniReporter
 {
@@ -778,6 +792,10 @@ nsMemoryReporterManager::Init()
     RegisterReporter(new ResidentReporter);
 #endif
 
+#ifdef HAVE_VSIZE_MAX_CONTIGUOUS_REPORTER
+    RegisterReporter(new VsizeMaxContiguousReporter);
+#endif
+
 #ifdef HAVE_RESIDENT_UNIQUE_REPORTER
     RegisterReporter(new ResidentUniqueReporter);
 #endif