diff --git a/gfx/thebes/gfxBlur.cpp b/gfx/thebes/gfxBlur.cpp
index 709bd1cd1d7d..6540dab67faa 100644
--- a/gfx/thebes/gfxBlur.cpp
+++ b/gfx/thebes/gfxBlur.cpp
@@ -12,6 +12,7 @@
 #include "mozilla/gfx/Blur.h"
 #include "mozilla/gfx/PathHelpers.h"
 #include "mozilla/Maybe.h"
+#include "mozilla/SystemGroup.h"
 #include "nsExpirationTracker.h"
 #include "nsClassHashtable.h"
 #include "gfxUtils.h"
@@ -351,7 +352,8 @@ class BlurCache final : public nsExpirationTracker<BlurCacheData,4>
 {
   public:
     BlurCache()
-      : nsExpirationTracker<BlurCacheData, 4>(GENERATION_MS, "BlurCache")
+      : nsExpirationTracker<BlurCacheData, 4>(GENERATION_MS, "BlurCache",
+                                              SystemGroup::EventTargetFor(TaskCategory::Other))
     {
     }
 
diff --git a/gfx/thebes/gfxGradientCache.cpp b/gfx/thebes/gfxGradientCache.cpp
index fa25bd78c826..c4c3389f1a35 100644
--- a/gfx/thebes/gfxGradientCache.cpp
+++ b/gfx/thebes/gfxGradientCache.cpp
@@ -8,6 +8,7 @@
 #include "PLDHashTable.h"
 #include "nsExpirationTracker.h"
 #include "nsClassHashtable.h"
+#include "mozilla/SystemGroup.h"
 #include "mozilla/Telemetry.h"
 #include "gfxGradientCache.h"
 #include <time.h>
@@ -123,7 +124,8 @@ class GradientCache final : public nsExpirationTracker<GradientCacheData,4>
   public:
     GradientCache()
       : nsExpirationTracker<GradientCacheData,4>(MAX_GENERATION_MS,
-                                                 "GradientCache")
+                                                 "GradientCache",
+                                                 SystemGroup::EventTargetFor(TaskCategory::Other))
     {
       srand(time(nullptr));
       mTimerPeriod = rand() % MAX_GENERATION_MS + 1;