diff --git a/gtsam/CMakeLists.txt b/gtsam/CMakeLists.txt
index d882f51e9..9dff36853 100644
--- a/gtsam/CMakeLists.txt
+++ b/gtsam/CMakeLists.txt
@@ -143,7 +143,7 @@ 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${Boost_INCLUDE_DIR})
+    set(mexFlags ${GTSAM_BUILD_MEX_BINARY_FLAGS} -I${MEX_INCLUDE_ROOT} -I${Boost_INCLUDE_DIR}  -I${CMAKE_BINARY_DIR})
 
     # Macro to handle details of setting up targets
     # FIXME: issue with dependency between wrap_gtsam and wrap_gtsam_build, only shows up on CMake 2.8.3
diff --git a/gtsam_unstable/CMakeLists.txt b/gtsam_unstable/CMakeLists.txt
index 954b6b4c1..d240ac4b8 100644
--- a/gtsam_unstable/CMakeLists.txt
+++ b/gtsam_unstable/CMakeLists.txt
@@ -99,7 +99,7 @@ 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${MEX_INCLUDE_ROOT} -I${Boost_INCLUDE_DIR})
+    set(mexFlags -I${MEX_INCLUDE_ROOT} -I${Boost_INCLUDE_DIR} -I${CMAKE_BINARY_DIR})
     
     # Macro to handle details of setting up targets
     wrap_library(gtsam_unstable "${mexFlags}" "./" gtsam)