diff --git a/src/os2/app.cpp b/src/os2/app.cpp
index 7daefe297d..bd4b47a6cf 100644
--- a/src/os2/app.cpp
+++ b/src/os2/app.cpp
@@ -44,6 +44,7 @@
 
 #else
 
+#include <nerrno.h>
 #include <ioctl.h>
 #include <select.h>
 
diff --git a/src/os2/utils.cpp b/src/os2/utils.cpp
index cf95be9855..94a7823eeb 100644
--- a/src/os2/utils.cpp
+++ b/src/os2/utils.cpp
@@ -35,30 +35,6 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-//
-// already defined via nerror.h in app.h so undef them
-//
-#ifdef EEXIST
-#undef EEXIST
-#endif
-#ifdef ENOENT
-#undef ENOENT
-#endif
-#ifdef EMFILE
-#undef EMFILE
-#endif
-#ifdef EINTR
-#undef EINTR
-#endif
-#ifdef EINVAL
-#undef EINVAL
-#endif
-#ifdef ENOMEM
-#undef ENOMEM
-#endif
-#ifdef EACCES
-#undef EACCES
-#endif
 #include <errno.h>
 #include <stdarg.h>
 
diff --git a/src/os2/utilsexc.cpp b/src/os2/utilsexc.cpp
index c13b9b3473..f9f3885e16 100644
--- a/src/os2/utilsexc.cpp
+++ b/src/os2/utilsexc.cpp
@@ -43,30 +43,6 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-//
-// already defined via nerror.h in app.h so undef them
-//
-#ifdef EEXIST
-#undef EEXIST
-#endif
-#ifdef ENOENT
-#undef ENOENT
-#endif
-#ifdef EMFILE
-#undef EMFILE
-#endif
-#ifdef EINTR
-#undef EINTR
-#endif
-#ifdef EINVAL
-#undef EINVAL
-#endif
-#ifdef ENOMEM
-#undef ENOMEM
-#endif
-#ifdef EACCES
-#undef EACCES
-#endif
 #include <errno.h>
 #include <stdarg.h>