diff --git a/cmake/cross_compiling/android.cmake b/cmake/cross_compiling/android.cmake
index 5b730743252c21248644d0b38b853b7a79b66c48..25081671477edc67dcb0f6f9b3a2f2f2e13c0fb6 100644
--- a/cmake/cross_compiling/android.cmake
+++ b/cmake/cross_compiling/android.cmake
@@ -74,8 +74,8 @@ IF(NOT DEFINED ANDROID_ARM_NEON)
     SET(ANDROID_ARM_NEON ON)
 ENDIF()
 
-IF(${CMAKE_VERSION} VERSION_LESS "3.7.0")  
-    IF(${CMAKE_VERSION} VERSION_LESS "3.1.0")
+IF("${CMAKE_VERSION}" VERSION_LESS "3.7.0")
+    IF("${CMAKE_VERSION}" VERSION_LESS "3.1.0")
         SET(CMAKE_SYSTEM_NAME "Linux")
     ENDIF()
     MESSAGE(WARNING "It is recommended to use CMake >= 3.7.0 (current version: "
diff --git a/cmake/external/protobuf.cmake b/cmake/external/protobuf.cmake
index 9892691a314e0b0fe67b2519730514edfbd3f3a0..c5dc5bee619995b2ee3e3689fd8a488f7cd42507 100644
--- a/cmake/external/protobuf.cmake
+++ b/cmake/external/protobuf.cmake
@@ -18,7 +18,7 @@ FUNCTION(build_protobuf TARGET_NAME BUILD_FOR_HOST)
     SET(PROTOBUF_SOURCES_DIR ${THIRD_PARTY_PATH}/${TARGET_NAME})
     SET(PROTOBUF_INSTALL_DIR ${THIRD_PARTY_PATH}/install/${TARGET_NAME})
 
-    SET(${TARGET_NAME}_INCLUDE_DIR "${PROTOBUF_INSTALL_DIR}/include"
+    SET(${TARGET_NAME}_INCLUDE_DIR "${PROTOBUF_INSTALL_DIR}/include")
     SET(PROTOBUF_INCLUDE_DIR "${PROTOBUF_INSTALL_DIR}/include" PARENT_SCOPE)
     SET(${TARGET_NAME}_LITE_LIBRARY
         "${PROTOBUF_INSTALL_DIR}/lib/libprotobuf-lite${STATIC_LIBRARY_SUFFIX}"