diff --git a/mpw/mpw.cpp b/mpw/mpw.cpp
index 7670252..7b3cbdc 100644
--- a/mpw/mpw.cpp
+++ b/mpw/mpw.cpp
@@ -73,52 +73,7 @@ namespace MPW
 
 	bool Trace = false;
 
-	int errno_to_errno(int xerrno)
-	{
-		switch (xerrno)
-		{
-		case EPERM: return kEPERM;
-		case ENOENT: return kENOENT;
 
-		#ifdef ENORSRC
-		case ENORSRC: return kENORSRC;
-		#endif
-
-		case EINTR: return kEINTR;
-		case EIO: return kEIO;
-		case ENXIO: return kENXIO;
-		case E2BIG: return kE2BIG;
-		case ENOEXEC: return kENOEXEC;
-		case EBADF: return kEBADF;
-		case ECHILD: return kECHILD;
-		case EAGAIN: return kEAGAIN;
-		case ENOMEM: return kENOMEM;
-		case EACCES: return kEACCES;
-		case EFAULT: return kEFAULT;
-		case ENOTBLK: return kENOTBLK;
-		case EBUSY: return kEBUSY;
-		case EEXIST: return kEEXIST;
-		case EXDEV: return kEXDEV;
-		case ENODEV: return kENODEV;
-		case ENOTDIR: return kENOTDIR;
-		case EISDIR: return kEISDIR;
-		case EINVAL: return kEINVAL;
-		case ENFILE: return kENFILE;
-		case EMFILE: return kEMFILE;
-		case ENOTTY: return kENOTTY;
-		case ETXTBSY: return kETXTBSY;
-		case EFBIG: return kEFBIG;
-		case ENOSPC: return kENOSPC;
-		case ESPIPE: return kESPIPE;
-		case EROFS: return kEROFS;
-		case EMLINK: return kEMLINK;
-		case EPIPE: return kEPIPE;
-		case EDOM: return kEDOM;
-		case ERANGE: return kERANGE;
-		}
-		return kEINVAL;
-
-	}
 
 	static bool isdir(const std::string &path)
 	{
diff --git a/mpw/mpw.h b/mpw/mpw.h
index 94b0a6d..742765a 100644
--- a/mpw/mpw.h
+++ b/mpw/mpw.h
@@ -119,8 +119,6 @@ namespace MPW {
 	void ftrap_write(uint16_t trap);
 	void ftrap_ioctl(uint16_t trap);
 
-	// native errno to an MPW errno.
-	int errno_to_errno(int xerrno);
 }
 
 #endif
\ No newline at end of file
diff --git a/mpw/mpw_access.cpp b/mpw/mpw_access.cpp
index f5a8f60..b7de0c2 100644
--- a/mpw/mpw_access.cpp
+++ b/mpw/mpw_access.cpp
@@ -133,7 +133,7 @@ namespace MPW
 		Log("     delete(%s)\n", sname.c_str());
 
 		rv = ::unlink(sname.c_str());
-		if (rv < 0) return 0x40000000 | errno_to_errno(errno);
+		if (rv < 0) return 0x40000000 | mpw_errno_from_errno();
 		
 		return 0;
 	}
@@ -192,7 +192,7 @@ namespace MPW
 		if (fd < 0)
 		{
 			// return an errno.
-			d0 = 0x40000000 | errno_to_errno(errno);
+			d0 = 0x40000000 | mpw_errno_from_errno();
 			f.error = MacOS::ioErr;
 			f.cookie = 0;
 		}
diff --git a/mpw/mpw_io.cpp b/mpw/mpw_io.cpp
index 1b5d00b..e48df99 100644
--- a/mpw/mpw_io.cpp
+++ b/mpw/mpw_io.cpp
@@ -26,6 +26,7 @@
 
 #include "mpw.h"
 #include "mpw_internal.h"
+#include "mpw_errno.h"
 
 #include <algorithm>
 #include <memory>
@@ -81,7 +82,7 @@ namespace MPW
 		{
 			//f.count = 0;
 			f.error = MacOS::ioErr; // ioErr
-			d0 = errno_to_errno(errno);
+			d0 = mpw_errno_from_errno();
 		}
 		else
 		{
@@ -126,7 +127,7 @@ namespace MPW
 		{
 			//f.count = 0;
 			f.error = MacOS::ioErr; // ioErr
-			d0 = errno_to_errno(errno);
+			d0 = mpw_errno_from_errno();
 		}
 		else
 		{
diff --git a/mpw/mpw_ioctl.cpp b/mpw/mpw_ioctl.cpp
index ac13fe6..19ee9e6 100644
--- a/mpw/mpw_ioctl.cpp
+++ b/mpw/mpw_ioctl.cpp
@@ -335,7 +335,7 @@ namespace MPW
 		off_t rv = ::lseek(fd, offset, nativeWhence);
 		if (rv < 0)
 		{
-			d0 = errno_to_errno(errno);
+			d0 = mpw_errno_from_errno();
 			f.error = macos_error_from_errno();
 			//perror(NULL);
 		}
@@ -376,7 +376,7 @@ namespace MPW
 				int ok = ftruncate(fd, arg);
 				if (ok == 0) return 0;
 				f.error = macos_error_from_errno();
-				return errno_to_errno(errno);
+				return (int)mpw_errno_from_errno();
 			},
 			[](int fd){
 				return kEINVAL;