diff --git a/gtsam/CMakeLists.txt b/gtsam/CMakeLists.txt
index 6ea73db30..9cb6d44d1 100644
--- a/gtsam/CMakeLists.txt
+++ b/gtsam/CMakeLists.txt
@@ -157,7 +157,8 @@ if (GTSAM_INSTALL_MATLAB_TOOLBOX)
 	set(GTSAM_LIB_DIR ${MEX_LIB_ROOT}/gtsam) # FIXME: is this used?
     
     # Generate, build and install toolbox
-    set(mexFlags ${GTSAM_BUILD_MEX_BINARY_FLAGS} -I${MEX_INCLUDE_ROOT} -I${TBB_INCLUDE_DIRS} -I${Boost_INCLUDE_DIR} -I${CMAKE_BINARY_DIR})
+    #set(mexFlags "${GTSAM_BUILD_MEX_BINARY_FLAGS} -I${MEX_INCLUDE_ROOT} -I${TBB_INCLUDE_DIRS} -I${Boost_INCLUDE_DIR} -I${CMAKE_BINARY_DIR}")
+    message("Additional mexFlags: [${mexFlags}]")
 	if("${gtsam-default}" STREQUAL "gtsam-static")
 		list(APPEND mexFlags -DGTSAM_IMPORT_STATIC)
 	endif()
diff --git a/gtsam_unstable/CMakeLists.txt b/gtsam_unstable/CMakeLists.txt
index 978c1d7e5..0cf6fe875 100644
--- a/gtsam_unstable/CMakeLists.txt
+++ b/gtsam_unstable/CMakeLists.txt
@@ -108,7 +108,7 @@ if (GTSAM_INSTALL_MATLAB_TOOLBOX)
 	set(GTSAM_UNSTABLE_LIB_DIR ${MEX_LIB_ROOT}/gtsam_unstable) # FIXME: is this used?
     
     # Generate, build and install toolbox
-    set(mexFlags -I${MEX_INCLUDE_ROOT} -I${TBB_INCLUDE_DIRS} -I${Boost_INCLUDE_DIR} -I${CMAKE_BINARY_DIR})
+    set(mexFlags "-I${MEX_INCLUDE_ROOT} -I${TBB_INCLUDE_DIRS} -I${Boost_INCLUDE_DIR} -I${CMAKE_BINARY_DIR}")
 	if("${gtsam-default}" STREQUAL "gtsam-static")
 		list(APPEND mexFlags -DGTSAM_IMPORT_STATIC)
 	endif()