diff --git a/include/gui/SurfaceTextureClient.h b/include/gui/SurfaceTextureClient.h
index e7c6e24..6ce44fc 100644
--- a/include/gui/SurfaceTextureClient.h
+++ b/include/gui/SurfaceTextureClient.h
@@ -80,6 +80,7 @@
     int setUsage(uint32_t reqUsage);
 
     void freeAllBuffers();
+    int getSlotFromBufferLocked(android_native_buffer_t* buffer) const;
 
     int getConnectedApi() const;
 
diff --git a/libs/gui/SurfaceTextureClient.cpp b/libs/gui/SurfaceTextureClient.cpp
index 22b0852..b9b2310 100644
--- a/libs/gui/SurfaceTextureClient.cpp
+++ b/libs/gui/SurfaceTextureClient.cpp
@@ -143,12 +143,40 @@
 int SurfaceTextureClient::cancelBuffer(android_native_buffer_t* buffer) {
     LOGV("SurfaceTextureClient::cancelBuffer");
     Mutex::Autolock lock(mMutex);
+    int i = getSlotFromBufferLocked(buffer);
+    if (i < 0) {
+        return i;
+    }
+    mSurfaceTexture->cancelBuffer(i);
+    return OK;
+}
+
+int SurfaceTextureClient::getSlotFromBufferLocked(
+        android_native_buffer_t* buffer) const {
+    bool dumpedState = false;
     for (int i = 0; i < NUM_BUFFER_SLOTS; i++) {
-        if (mSlots[i]->handle == buffer->handle) {
-            mSurfaceTexture->cancelBuffer(i);
-            return OK;
+        // XXX: Dump the slots whenever we hit a NULL entry while searching for
+        // a buffer.
+        if (mSlots[i] == NULL) {
+            if (!dumpedState) {
+                LOGD("getSlotFromBufferLocked: encountered NULL buffer in slot %d "
+                        "looking for buffer %p", i, buffer->handle);
+                for (int j = 0; j < NUM_BUFFER_SLOTS; j++) {
+                    if (mSlots[j] == NULL) {
+                        LOGD("getSlotFromBufferLocked:   %02d: NULL", j);
+                    } else {
+                        LOGD("getSlotFromBufferLocked:   %02d: %p", j, mSlots[j]->handle);
+                    }
+                }
+                dumpedState = true;
+            }
+        }
+
+        if (mSlots[i] != NULL && mSlots[i]->handle == buffer->handle) {
+            return i;
         }
     }
+    LOGE("getSlotFromBufferLocked: unknown buffer: %p", buffer->handle);
     return BAD_VALUE;
 }
 
@@ -169,13 +197,12 @@
     } else {
         timestamp = mTimestamp;
     }
-    for (int i = 0; i < NUM_BUFFER_SLOTS; i++) {
-        if (mSlots[i]->handle == buffer->handle) {
-            return mSurfaceTexture->queueBuffer(i, timestamp);
-        }
+    int i = getSlotFromBufferLocked(buffer);
+    if (i < 0) {
+        return i;
     }
-    LOGE("queueBuffer: unknown buffer queued");
-    return BAD_VALUE;
+    mSurfaceTexture->queueBuffer(i, timestamp);
+    return OK;
 }
 
 int SurfaceTextureClient::query(int what, int* value) const {
diff --git a/libs/gui/tests/SurfaceTexture_test.cpp b/libs/gui/tests/SurfaceTexture_test.cpp
index f6cefa6..f219639 100644
--- a/libs/gui/tests/SurfaceTexture_test.cpp
+++ b/libs/gui/tests/SurfaceTexture_test.cpp
@@ -173,11 +173,11 @@
     }
 
     virtual EGLint getSurfaceWidth() {
-        return 64;
+        return 512;
     }
 
     virtual EGLint getSurfaceHeight() {
-        return 64;
+        return 512;
     }
 
     void loadShader(GLenum shaderType, const char* pSource, GLuint* outShader) {
@@ -526,18 +526,19 @@
     glClearColor(0.2, 0.2, 0.2, 0.2);
     glClear(GL_COLOR_BUFFER_BIT);
 
+    glViewport(0, 0, texWidth, texHeight);
     drawTexture();
 
     EXPECT_TRUE(checkPixel( 0,  0, 255, 127, 255, 255));
     EXPECT_TRUE(checkPixel(63,  0,   0, 133,   0, 255));
-    EXPECT_TRUE(checkPixel(63, 63,   0, 133,   0, 255));
-    EXPECT_TRUE(checkPixel( 0, 63, 255, 127, 255, 255));
+    EXPECT_TRUE(checkPixel(63, 65,   0, 133,   0, 255));
+    EXPECT_TRUE(checkPixel( 0, 65, 255, 127, 255, 255));
 
-    EXPECT_TRUE(checkPixel(22, 44, 247,  70, 255, 255));
-    EXPECT_TRUE(checkPixel(45, 52, 209,  32, 235, 255));
-    EXPECT_TRUE(checkPixel(52, 51, 100, 255,  73, 255));
+    EXPECT_TRUE(checkPixel(22, 44, 255, 127, 255, 255));
+    EXPECT_TRUE(checkPixel(45, 52, 255, 127, 255, 255));
+    EXPECT_TRUE(checkPixel(52, 51,  98, 255,  73, 255));
     EXPECT_TRUE(checkPixel( 7, 31, 155,   0, 118, 255));
-    EXPECT_TRUE(checkPixel(31,  9, 148,  71, 110, 255));
+    EXPECT_TRUE(checkPixel(31,  9, 107,  24,  87, 255));
     EXPECT_TRUE(checkPixel(29, 35, 255, 127, 255, 255));
     EXPECT_TRUE(checkPixel(36, 22, 155,  29,   0, 255));
 }
@@ -570,6 +571,7 @@
     glClearColor(0.2, 0.2, 0.2, 0.2);
     glClear(GL_COLOR_BUFFER_BIT);
 
+    glViewport(0, 0, texWidth, texHeight);
     drawTexture();
 
     EXPECT_TRUE(checkPixel( 0,  0,   0, 133,   0, 255));
@@ -628,6 +630,7 @@
         glClearColor(0.2, 0.2, 0.2, 0.2);
         glClear(GL_COLOR_BUFFER_BIT);
 
+        glViewport(0, 0, 64, 64);
         drawTexture();
 
         EXPECT_TRUE(checkPixel( 0,  0,  82, 255,  35, 255));
@@ -675,28 +678,29 @@
     glClearColor(0.2, 0.2, 0.2, 0.2);
     glClear(GL_COLOR_BUFFER_BIT);
 
+    glViewport(0, 0, texWidth, texHeight);
     drawTexture();
 
     EXPECT_TRUE(checkPixel( 0,  0,  35,  35,  35,  35));
     EXPECT_TRUE(checkPixel(63,  0, 231, 231, 231, 231));
-    EXPECT_TRUE(checkPixel(63, 63, 231, 231, 231, 231));
-    EXPECT_TRUE(checkPixel( 0, 63,  35,  35,  35,  35));
+    EXPECT_TRUE(checkPixel(63, 65, 231, 231, 231, 231));
+    EXPECT_TRUE(checkPixel( 0, 65,  35,  35,  35,  35));
 
     EXPECT_TRUE(checkPixel(15, 10,  35, 231, 231, 231));
-    EXPECT_TRUE(checkPixel(24, 63,  35, 231, 231,  35));
-    EXPECT_TRUE(checkPixel(19, 40,  87, 179,  35,  35));
+    EXPECT_TRUE(checkPixel(24, 63,  38, 228, 231,  35));
+    EXPECT_TRUE(checkPixel(19, 40,  35, 231,  35,  35));
     EXPECT_TRUE(checkPixel(38, 30, 231,  35,  35,  35));
     EXPECT_TRUE(checkPixel(42, 54,  35,  35,  35, 231));
-    EXPECT_TRUE(checkPixel(37, 33,  35, 231, 231, 231));
+    EXPECT_TRUE(checkPixel(37, 33, 228,  38,  38,  38));
     EXPECT_TRUE(checkPixel(31,  8, 231,  35,  35, 231));
-    EXPECT_TRUE(checkPixel(36, 47, 231,  35, 231, 231));
-    EXPECT_TRUE(checkPixel(24, 63,  35, 231, 231,  35));
-    EXPECT_TRUE(checkPixel(48,  3, 231, 231,  35,  35));
+    EXPECT_TRUE(checkPixel(36, 47, 228,  35, 231, 231));
+    EXPECT_TRUE(checkPixel(24, 63,  38, 228, 231,  35));
+    EXPECT_TRUE(checkPixel(48,  3, 228, 228,  38,  35));
     EXPECT_TRUE(checkPixel(54, 50,  35, 231, 231, 231));
-    EXPECT_TRUE(checkPixel(24, 25, 191, 191, 231, 231));
-    EXPECT_TRUE(checkPixel(10,  9,  93,  93, 231, 231));
+    EXPECT_TRUE(checkPixel(24, 25,  41,  41, 231, 231));
+    EXPECT_TRUE(checkPixel(10,  9,  38,  38, 231, 231));
     EXPECT_TRUE(checkPixel(29,  4,  35,  35,  35, 231));
-    EXPECT_TRUE(checkPixel(56, 31,  35, 231, 231,  35));
+    EXPECT_TRUE(checkPixel(56, 31,  38, 228, 231,  35));
     EXPECT_TRUE(checkPixel(58, 55,  35,  35, 231, 231));
 }
 
@@ -730,6 +734,7 @@
     glClearColor(0.2, 0.2, 0.2, 0.2);
     glClear(GL_COLOR_BUFFER_BIT);
 
+    glViewport(0, 0, texWidth, texHeight);
     drawTexture();
 
     EXPECT_TRUE(checkPixel( 0,  0, 231, 231, 231, 231));
@@ -803,6 +808,7 @@
     glClearColor(0.2, 0.2, 0.2, 0.2);
     glClear(GL_COLOR_BUFFER_BIT);
 
+    glViewport(0, 0, texWidth, texHeight);
     drawTexture();
 
     EXPECT_TRUE(checkPixel( 0,  0, 153, 153, 153, 153));