diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 0e7c214..406debf 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -2627,10 +2627,19 @@
         // or we will break the contract where WM can treat child surfaces as
         // pixels in the parent surface.
         if (p->isFixedSize()) {
+            int bufferWidth;
+            int bufferHeight;
+            if ((p->mCurrentTransform & NATIVE_WINDOW_TRANSFORM_ROT_90) == 0) {
+                bufferWidth = p->mActiveBuffer->getWidth();
+                bufferHeight = p->mActiveBuffer->getHeight();
+            } else {
+                bufferHeight = p->mActiveBuffer->getWidth();
+                bufferWidth = p->mActiveBuffer->getHeight();
+            }
             float sx = p->getDrawingState().active.w /
-                    static_cast<float>(p->mActiveBuffer->getWidth());
+                    static_cast<float>(bufferWidth);
             float sy = p->getDrawingState().active.h /
-                    static_cast<float>(p->mActiveBuffer->getHeight());
+                    static_cast<float>(bufferHeight);
             Transform extraParentScaling;
             extraParentScaling.set(sx, 0, 0, sy);
             t = t * extraParentScaling;
diff --git a/services/surfaceflinger/tests/Transaction_test.cpp b/services/surfaceflinger/tests/Transaction_test.cpp
index 7a8b4ab..5474fda 100644
--- a/services/surfaceflinger/tests/Transaction_test.cpp
+++ b/services/surfaceflinger/tests/Transaction_test.cpp
@@ -941,4 +941,40 @@
     }
 }
 
+// Regression test for b/37673612
+TEST_F(ChildLayerTest, ChildrenWithParentBufferTransform) {
+    SurfaceComposerClient::openGlobalTransaction();
+    mChild->show();
+    mChild->setPosition(0, 0);
+    mFGSurfaceControl->setPosition(0, 0);
+    SurfaceComposerClient::closeGlobalTransaction(true);
+
+    {
+        ScreenCapture::captureScreen(&mCapture);
+        // We've positioned the child in the top left.
+        mCapture->expectChildColor(0, 0);
+        // But it's only 10x10.
+        mCapture->expectFGColor(10, 10);
+    }
+
+
+    // We set things up as in b/37673612 so that there is a mismatch between the buffer size and
+    // the WM specified state size.
+    mFGSurfaceControl->setSize(128, 64);
+    sp<Surface> s = mFGSurfaceControl->getSurface();
+    auto anw = static_cast<ANativeWindow*>(s.get());
+    native_window_set_buffers_transform(anw, NATIVE_WINDOW_TRANSFORM_ROT_90);
+    native_window_set_buffers_dimensions(anw, 64, 128);
+    fillSurfaceRGBA8(mFGSurfaceControl, 195, 63, 63);
+    waitForPostedBuffers();
+
+    {
+        // The child should still be in the same place and not have any strange scaling as in
+        // b/37673612.
+        ScreenCapture::captureScreen(&mCapture);
+        mCapture->expectChildColor(0, 0);
+        mCapture->expectFGColor(10, 10);
+    }
+}
+
 }