diff --git a/tools/emulator/system/camera/EmulatedFakeCamera2.cpp b/tools/emulator/system/camera/EmulatedFakeCamera2.cpp
index 426f6731d..52ae2493d 100644
--- a/tools/emulator/system/camera/EmulatedFakeCamera2.cpp
+++ b/tools/emulator/system/camera/EmulatedFakeCamera2.cpp
@@ -1136,6 +1136,7 @@ void EmulatedFakeCamera2::ReadoutThread::setNextOperation(
         camera_metadata_t *request,
         Buffers *buffers) {
     Mutex::Autolock lock(mInputMutex);
+    Mutex::Autolock iLock(mInternalsMutex);
     if ( !readyForNextCapture() ) {
         ALOGE("In flight queue full, dropping captures");
         mParent->signalError();