diff --git a/tensorflow/lite/tools/make/Makefile b/tensorflow/lite/tools/make/Makefile
index 8699e13b12f..0b9c99c52aa 100644
--- a/tensorflow/lite/tools/make/Makefile
+++ b/tensorflow/lite/tools/make/Makefile
@@ -59,7 +59,6 @@ CXXFLAGS := -O3 -DNDEBUG -fPIC
 CXXFLAGS += $(EXTRA_CXXFLAGS)
 CFLAGS := ${CXXFLAGS}
 CXXFLAGS += --std=c++11
-CFLAGS :=
 LDOPTS := -L/usr/local/lib
 ARFLAGS := -r
 TARGET_TOOLCHAIN_PREFIX :=
@@ -166,6 +165,7 @@ ifeq ($(BUILD_WITH_NNAPI),true)
 	CORE_CC_ALL_SRCS += tensorflow/lite/delegates/nnapi/nnapi_delegate.cc
 	CORE_CC_ALL_SRCS += tensorflow/lite/nnapi/nnapi_implementation.cc
 	CORE_CC_ALL_SRCS += tensorflow/lite/nnapi/quant_lstm_sup.cc
+	LIBS += -lrt
 else
 	CORE_CC_ALL_SRCS += tensorflow/lite/delegates/nnapi/nnapi_delegate_disabled.cc
 	CORE_CC_ALL_SRCS += tensorflow/lite/nnapi/nnapi_implementation_disabled.cc