diff --git a/services/surfaceflinger/tests/fakehwc/FakeComposerClient.cpp b/services/surfaceflinger/tests/fakehwc/FakeComposerClient.cpp
index 60916f3..d97ffa3 100644
--- a/services/surfaceflinger/tests/fakehwc/FakeComposerClient.cpp
+++ b/services/surfaceflinger/tests/fakehwc/FakeComposerClient.cpp
@@ -36,7 +36,6 @@
 #include <thread>
 
 constexpr Config NULL_DISPLAY_CONFIG = static_cast<Config>(0);
-constexpr Display DEFAULT_DISPLAY = static_cast<Display>(1);
 
 using namespace sftest;
 
@@ -168,7 +167,7 @@
     ALOGV("enableCallback");
     mCallbacksOn = enable;
     if (mCallbacksOn) {
-        mClient->onHotplug(DEFAULT_DISPLAY, IComposerCallback::Connection::CONNECTED);
+        mClient->onHotplug(PRIMARY_DISPLAY, IComposerCallback::Connection::CONNECTED);
     }
 }
 
@@ -507,7 +506,7 @@
         if (mSurfaceComposer != nullptr) {
             mSurfaceComposer->injectVSync(timestamp);
         } else {
-            mClient->onVsync(DEFAULT_DISPLAY, timestamp);
+            mClient->onVsync(PRIMARY_DISPLAY, timestamp);
         }
     }
 }
diff --git a/services/surfaceflinger/tests/fakehwc/FakeComposerClient.h b/services/surfaceflinger/tests/fakehwc/FakeComposerClient.h
index 294abb2..2a5a8ad 100644
--- a/services/surfaceflinger/tests/fakehwc/FakeComposerClient.h
+++ b/services/surfaceflinger/tests/fakehwc/FakeComposerClient.h
@@ -19,6 +19,9 @@
 #include "ComposerClient.h"
 #include "RenderState.h"
 
+// Needed for display type/ID enums
+#include <hardware/hwcomposer_defs.h>
+
 #include <utils/Condition.h>
 
 #include <chrono>
@@ -40,6 +43,13 @@
 
 namespace sftest {
 
+// NOTE: The ID's need to be exactly these. VR composer and parts of
+// the SurfaceFlinger assume the display IDs to have these values
+// despite the enum being documented as a display type.
+// TODO: Reference to actual documentation
+constexpr Display PRIMARY_DISPLAY = static_cast<Display>(HWC_DISPLAY_PRIMARY);
+constexpr Display EXTERNAL_DISPLAY = static_cast<Display>(HWC_DISPLAY_EXTERNAL);
+
 class FakeComposerClient : public ComposerBase {
 public:
     FakeComposerClient();
diff --git a/services/surfaceflinger/tests/fakehwc/SFFakeHwc_test.cpp b/services/surfaceflinger/tests/fakehwc/SFFakeHwc_test.cpp
index 8902ede..9ac3331 100644
--- a/services/surfaceflinger/tests/fakehwc/SFFakeHwc_test.cpp
+++ b/services/surfaceflinger/tests/fakehwc/SFFakeHwc_test.cpp
@@ -168,17 +168,15 @@
     android::hardware::ProcessState::self()->startThreadPool();
     android::ProcessState::self()->startThreadPool();
 
-    EXPECT_CALL(*mMockComposer, getDisplayType(1, _))
+    EXPECT_CALL(*mMockComposer, getDisplayType(PRIMARY_DISPLAY, _))
             .WillOnce(DoAll(SetArgPointee<1>(IComposerClient::DisplayType::PHYSICAL),
                             Return(Error::NONE)));
-    // Seems to be doubled right now, once for display ID 1 and once for 0. This sounds fishy
-    // but encoding that here exactly.
-    EXPECT_CALL(*mMockComposer, getDisplayAttribute(1, 1, _, _))
-            .Times(5)
-            .WillRepeatedly(Invoke(mMockComposer, &MockComposerClient::getDisplayAttributeFake));
-    // TODO: Find out what code is generating the ID 0.
-    EXPECT_CALL(*mMockComposer, getDisplayAttribute(0, 1, _, _))
-            .Times(5)
+    // Primary display will be queried twice for all 5 attributes. One
+    // set of queries comes from the SurfaceFlinger proper an the
+    // other set from the VR composer.
+    // TODO: Is VR composer always present? Change to atLeast(5)?
+    EXPECT_CALL(*mMockComposer, getDisplayAttribute(PRIMARY_DISPLAY, 1, _, _))
+            .Times(2 * 5)
             .WillRepeatedly(Invoke(mMockComposer, &MockComposerClient::getDisplayAttributeFake));
 
     startSurfaceFlinger();
@@ -207,31 +205,32 @@
 TEST_F(DisplayTest, Hotplug) {
     ALOGD("DisplayTest::Hotplug");
 
-    EXPECT_CALL(*mMockComposer, getDisplayType(2, _))
+    EXPECT_CALL(*mMockComposer, getDisplayType(EXTERNAL_DISPLAY, _))
             .Times(2)
             .WillRepeatedly(DoAll(SetArgPointee<1>(IComposerClient::DisplayType::PHYSICAL),
                                   Return(Error::NONE)));
     // The attribute queries will get done twice. This is for defaults
-    EXPECT_CALL(*mMockComposer, getDisplayAttribute(2, 1, _, _))
+    EXPECT_CALL(*mMockComposer, getDisplayAttribute(EXTERNAL_DISPLAY, 1, _, _))
             .Times(2 * 3)
             .WillRepeatedly(Invoke(mMockComposer, &MockComposerClient::getDisplayAttributeFake));
     // ... and then special handling for dimensions. Specifying this
     // rules later means that gmock will try them first, i.e.,
     // ordering of width/height vs. the default implementation for
     // other queries is significant.
-    EXPECT_CALL(*mMockComposer, getDisplayAttribute(2, 1, IComposerClient::Attribute::WIDTH, _))
+    EXPECT_CALL(*mMockComposer,
+                getDisplayAttribute(EXTERNAL_DISPLAY, 1, IComposerClient::Attribute::WIDTH, _))
             .Times(2)
             .WillRepeatedly(DoAll(SetArgPointee<3>(400), Return(Error::NONE)));
 
-    EXPECT_CALL(*mMockComposer, getDisplayAttribute(2, 1, IComposerClient::Attribute::HEIGHT, _))
+    EXPECT_CALL(*mMockComposer,
+                getDisplayAttribute(EXTERNAL_DISPLAY, 1, IComposerClient::Attribute::HEIGHT, _))
             .Times(2)
             .WillRepeatedly(DoAll(SetArgPointee<3>(200), Return(Error::NONE)));
 
     // TODO: Width and height queries are not actually called. Display
     // info returns dimensions 0x0 in display info. Why?
 
-    mMockComposer->hotplugDisplay(static_cast<Display>(2),
-                                  IComposerCallback::Connection::CONNECTED);
+    mMockComposer->hotplugDisplay(EXTERNAL_DISPLAY, IComposerCallback::Connection::CONNECTED);
 
     {
         sp<android::IBinder> display(
@@ -257,13 +256,11 @@
         }
     }
 
-    mMockComposer->hotplugDisplay(static_cast<Display>(2),
-                                  IComposerCallback::Connection::DISCONNECTED);
+    mMockComposer->hotplugDisplay(EXTERNAL_DISPLAY, IComposerCallback::Connection::DISCONNECTED);
 
     mMockComposer->clearFrames();
 
-    mMockComposer->hotplugDisplay(static_cast<Display>(2),
-                                  IComposerCallback::Connection::CONNECTED);
+    mMockComposer->hotplugDisplay(EXTERNAL_DISPLAY, IComposerCallback::Connection::CONNECTED);
 
     {
         sp<android::IBinder> display(
@@ -288,8 +285,7 @@
             ASSERT_EQ(NO_ERROR, surfaceControl->show());
         }
     }
-    mMockComposer->hotplugDisplay(static_cast<Display>(2),
-                                  IComposerCallback::Connection::DISCONNECTED);
+    mMockComposer->hotplugDisplay(EXTERNAL_DISPLAY, IComposerCallback::Connection::DISCONNECTED);
 }
 
 ////////////////////////////////////////////////
@@ -664,7 +660,7 @@
              {{0.f, 1.f, 1.f, 0.f},     HWC_TRANSFORM_FLIP_H_ROT_90,    {64, 64, 128, 128}},
              {{0.f, 1.f, 1.f, 0.f},     HWC_TRANSFORM_FLIP_V_ROT_90,    {64, 64, 128, 128}}};
     // clang-format on
-    constexpr int TEST_COUNT = sizeof(MATRIX_TESTS)/sizeof(matrixTestData);
+    constexpr int TEST_COUNT = sizeof(MATRIX_TESTS) / sizeof(matrixTestData);
 
     for (int i = 0; i < TEST_COUNT; i++) {
         // TODO: How to leverage the HWC2 stringifiers?