diff --git a/layout/base/nsPresShell.cpp b/layout/base/nsPresShell.cpp
index 1ba8870cb23..abb1299da55 100644
--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -7506,9 +7506,10 @@ PresShell::ProcessReflowCommands(bool aInterruptible)
     UnsuppressAndInvalidate();
   }
 
-  if (mDocument->GetRootElement() && mDocument->GetRootElement()->IsXUL()) {
-    mozilla::Telemetry::AccumulateTimeDelta(Telemetry::XUL_REFLOW_MS,
-                                            timerStart);
+  if (mDocument->GetRootElement()) {
+    Telemetry::ID id = (mDocument->GetRootElement()->IsXUL()
+                        ? Telemetry::XUL_REFLOW_MS : Telemetry::HTML_REFLOW_MS);
+    Telemetry::AccumulateTimeDelta(id, timerStart);
   }
 
   return !interrupted;
diff --git a/toolkit/components/telemetry/TelemetryHistograms.h b/toolkit/components/telemetry/TelemetryHistograms.h
index 42516249e16..1205203ddc0 100644
--- a/toolkit/components/telemetry/TelemetryHistograms.h
+++ b/toolkit/components/telemetry/TelemetryHistograms.h
@@ -314,7 +314,8 @@ HISTOGRAM_BOOLEAN(FX_CONTEXT_SEARCH_AND_TAB_SELECT, "Firefox: Background tab was
 // #endif
 
 HISTOGRAM_BOOLEAN(INNERWINDOWS_WITH_MUTATION_LISTENERS, "Deleted or to-be-reused innerwindow which has had mutation event listeners.")
-HISTOGRAM(XUL_REFLOW_MS, 1, 3000, 10, EXPONENTIAL, "xul reflows")
+HISTOGRAM(XUL_REFLOW_MS, 1, 3000, 10, EXPONENTIAL, "XUL reflows (ms)")
+HISTOGRAM(HTML_REFLOW_MS, 1, 3000, 10, EXPONENTIAL, "HTML reflows (ms)")
 HISTOGRAM(XUL_INITIAL_FRAME_CONSTRUCTION, 1, 3000, 10, EXPONENTIAL, "initial xul frame construction")
 HISTOGRAM_BOOLEAN(XMLHTTPREQUEST_ASYNC_OR_SYNC, "Type of XMLHttpRequest, async or sync")