diff --git a/matlab/include/engine.h b/matlab/include/engine.h
index 9b1b545..d285a85 100644
--- a/matlab/include/engine.h
+++ b/matlab/include/engine.h
@@ -7,7 +7,6 @@
 extern "C" {
 #endif
 
-  typedef struct mxArray_tag mxArray;
   typedef struct engine Engine;
 
   int engEvalString(Engine *, const char *);