diff --git a/contrib/CMakeLists.txt b/contrib/CMakeLists.txt
index 48905fcbfadb76d9a8356c52b38f87533df5b583..0d02634c7e350501a741a4c51d07981dccaeb438 100644
--- a/contrib/CMakeLists.txt
+++ b/contrib/CMakeLists.txt
@@ -230,7 +230,7 @@ endif(${BUILD_WITH_LEVELDB})
 if(${BUILD_WITH_ROCKSDB})
     if(${TD_LINUX})
         SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS_REL} -Wno-error=maybe-uninitialized -Wno-error=unused-but-set-variable -Wno-error=unused-variable -Wno-error=unused-function -Wno-errno=unused-private-field -Wno-error=unused-result")
-        if(NOT ${CMAKE_BUILD_TYPE})
+        IF ("${CMAKE_BUILD_TYPE}" STREQUAL "")
             SET(CMAKE_BUILD_TYPE Release)
         endif()
     endif(${TD_LINUX})
@@ -491,8 +491,8 @@ if(${BUILD_GEOS})
     if(${TD_LINUX})
         set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS_REL}")
         set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS_REL}")
-        if(NOT ${CMAKE_BUILD_TYPE})
-            set(CMAKE_BUILD_TYPE Release)
+        IF ("${CMAKE_BUILD_TYPE}" STREQUAL "")
+            SET(CMAKE_BUILD_TYPE Release)
         endif()
     endif(${TD_LINUX})
     option(BUILD_SHARED_LIBS "Build GEOS with shared libraries" OFF)