diff --git a/sim/hei_sim_main.cpp b/sim/hei_sim_main.cpp
index 035d003..7ddf7b4 100644
--- a/sim/hei_sim_main.cpp
+++ b/sim/hei_sim_main.cpp
@@ -3,7 +3,7 @@
 
 int main()
 {
-    HEI::Isolator iso;
+    libhei::Isolator iso;
 
     iso.initialize();
 
diff --git a/sim/hei_trace.hpp b/sim/hei_trace.hpp
deleted file mode 100644
index ebb2a8e..0000000
--- a/sim/hei_trace.hpp
+++ /dev/null
@@ -1,3 +0,0 @@
-#include <stdio.h>
-
-#define HEI_TRAC(...) printf( __VA_ARGS__ ); printf( "\n" );
diff --git a/sim/hei_user_defines.hpp b/sim/hei_user_defines.hpp
new file mode 100644
index 0000000..54c7344
--- /dev/null
+++ b/sim/hei_user_defines.hpp
@@ -0,0 +1,18 @@
+#include <stdio.h>
+#include <assert.h>
+
+#define HEI_INF( ... ) \
+{ \
+  printf( "I> " __VA_ARGS__ ); \
+  printf( "\n" ); \
+}
+
+#define HEI_ERR( ... ) \
+{ \
+  printf( "E> " __VA_ARGS__ ); \
+  printf( "\n" ); \
+}
+
+#define HEI_ASSERT( expression ) \
+  assert( expression );
+