diff --git a/libs/gui/SurfaceComposerClient.cpp b/libs/gui/SurfaceComposerClient.cpp
index 0f5192d..7001339 100644
--- a/libs/gui/SurfaceComposerClient.cpp
+++ b/libs/gui/SurfaceComposerClient.cpp
@@ -1274,6 +1274,12 @@
         mStatus = BAD_INDEX;
         return *this;
     }
+    if (alpha < 0.0f || alpha > 1.0f) {
+        ALOGE("SurfaceComposerClient::Transaction::setAlpha: invalid alpha %f", alpha);
+        mStatus = BAD_VALUE;
+        return *this;
+
+    }
     s->what |= layer_state_t::eAlphaChanged;
     s->alpha = alpha;