diff --git a/gtsam/3rdparty/CCOLAMD/Source/ccolamd.c b/gtsam/3rdparty/CCOLAMD/Source/ccolamd.c
index 36ffa1ada..49a4d8f60 100644
--- a/gtsam/3rdparty/CCOLAMD/Source/ccolamd.c
+++ b/gtsam/3rdparty/CCOLAMD/Source/ccolamd.c
@@ -617,11 +617,11 @@
 
 #include "ccolamd.h"
 
-#include <stdlib.h>
 #include <math.h>
 #include <limits.h>
 
 #ifdef MATLAB_MEX_FILE
+typedef uint16_t char16_t;
 #include "mex.h"
 #include "matrix.h"
 #endif
diff --git a/gtsam/3rdparty/CCOLAMD/Source/ccolamd_global.c b/gtsam/3rdparty/CCOLAMD/Source/ccolamd_global.c
index d43985126..10c9fd5be 100644
--- a/gtsam/3rdparty/CCOLAMD/Source/ccolamd_global.c
+++ b/gtsam/3rdparty/CCOLAMD/Source/ccolamd_global.c
@@ -13,6 +13,8 @@
 
 #ifndef NPRINT
 #ifdef MATLAB_MEX_FILE
+#include <stdlib.h>
+typedef uint16_t char16_t;
 #include "mex.h"
 int (*ccolamd_printf) (const char *, ...) = mexPrintf ;
 #else