diff --git a/mpw/mpw_access.cpp b/mpw/mpw_access.cpp
index 2bf253f..209d39f 100644
--- a/mpw/mpw_access.cpp
+++ b/mpw/mpw_access.cpp
@@ -22,6 +22,10 @@
 #include <toolbox/toolbox.h>
 #include <toolbox/os.h>
 
+/*
+ * access return errors are |= 0x40000000.  Not entirely sure why...
+ * may return an errno or an oserr, too, apparently.
+ */
 
 
 namespace MPW
@@ -79,7 +83,7 @@ namespace MPW
 
 		if (fd < 0)
 		{
-			// why the 0x40... ??
+			// return an errno.
 			d0 = 0x40000000 | errno_to_errno(errno);
 			f.error = -36; // ioErr ... whatever.
 			f.cookie = 0;
diff --git a/mpw/mpw_io.cpp b/mpw/mpw_io.cpp
index dd3113a..4469903 100644
--- a/mpw/mpw_io.cpp
+++ b/mpw/mpw_io.cpp
@@ -75,7 +75,7 @@ namespace MPW
 			{
 				//f.count = 0;
 				f.error = OS::ioErr; // ioErr
-				d0 = 0x40000000 | errno_to_errno(errno);
+				d0 = errno_to_errno(errno);
 			}
 			else
 			{
@@ -140,7 +140,7 @@ namespace MPW
 			{
 				//f.count = 0;
 				f.error = -36; // ioErr
-				d0 = 0x40000000 | errno_to_errno(errno);
+				d0 = errno_to_errno(errno);
 			}
 			else
 			{
diff --git a/mpw/mpw_ioctl.cpp b/mpw/mpw_ioctl.cpp
index 90a9d7e..07841d1 100644
--- a/mpw/mpw_ioctl.cpp
+++ b/mpw/mpw_ioctl.cpp
@@ -48,7 +48,7 @@ namespace MPW
 
 		if (fd < 0 || fd >= FDTable.size() || !FDTable[fd])
 		{
-			d0 = kEINVAL; // | 0x40000000 ?
+			d0 = kEINVAL;
 		}
 		else
 		{