diff --git a/ChangeLog b/ChangeLog
index 9507e44..ea87d74 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2014-01-23  <rfranke>
+
+	* hxi/Hxi_SimStruct.[hC]:
+	  - move mxFree into the compilation unit that allocates memory
+
 2014-01-22  <rfranke>
 
 	* README.html, README.md, INSTALL.html, Makefile, doc/Doxyfile.in:
diff --git a/hxi/Hxi_SimStruct.C b/hxi/Hxi_SimStruct.C
index d9b06aa..fe44e40 100644
--- a/hxi/Hxi_SimStruct.C
+++ b/hxi/Hxi_SimStruct.C
@@ -9,7 +9,7 @@
  */
 
 /*
-    Copyright (C) 1994--2010  Ruediger Franke
+    Copyright (C) 1994--2014  Ruediger Franke
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
@@ -1136,6 +1136,11 @@ HXI_EXTERN void Hxi_SimStruct_destroy(SimStruct *S) {
     delete (Hxi::SimStruct<real_T>*)S;
 }
 
+/* Free memory allocated through mx methods, e.g. mxArrayToString. */
+HXI_EXTERN void mxFree(void *p) {
+  free(p);
+}
+
 #if !defined(HXI_INLINE_S_FUNCTION)
 
 /** Initialize SimStruct for specific model. */
diff --git a/hxi/Hxi_SimStruct.h b/hxi/Hxi_SimStruct.h
index 35272b0..512bb31 100644
--- a/hxi/Hxi_SimStruct.h
+++ b/hxi/Hxi_SimStruct.h
@@ -40,9 +40,6 @@
 /** @name Definitions used outside S-functions as well */
 /*@{*/
 #define CONTINUOUS_SAMPLE_TIME 			0.0
-
-/** Free memory allocated though mx methods, e.g. mxArrayToString. */
-#define mxFree(p)	free(p)
 /*@}*/
 
 /* forward declare SimStruct and mxArray */
@@ -75,6 +72,9 @@ HXI_EXTERN SimStruct *Hxi_SimStruct_create(const char *path);
 /** Delete a SimStruct. */
 HXI_EXTERN void Hxi_SimStruct_destroy(SimStruct *S);
 
+/** Free memory allocated though mx methods, e.g. mxArrayToString. */
+HXI_EXTERN void mxFree(void *p);
+
 #if !defined(HXI_INLINE_S_FUNCTION)
 /** @name Supported S-function methods. */
 /*@{*/