diff --git a/src/remap_os_error.c b/src/remap_os_error.c
index 85f991e..77d6a90 100644
--- a/src/remap_os_error.c
+++ b/src/remap_os_error.c
@@ -10,7 +10,11 @@ int remap_os_error(unsigned long e) {
 	
 	switch(e) {
 	case NO_ERROR: return 0;
-	default: return EIO;
+	default:
+	#ifdef ELAST
+		if (e > ELAST) return e;
+	#endif 
+		return EIO;
 
     case ERROR_INVALID_HANDLE:
     	return EBADF;
@@ -24,7 +28,6 @@ int remap_os_error(unsigned long e) {
     case ERROR_WRITE_FAULT:
     	return EIO;
 
-
     case ERROR_ACCESS_DENIED:
     case ERROR_CANNOT_MAKE:
     case ERROR_CURRENT_DIRECTORY: