diff --git a/libsrc/cbm/read.s b/libsrc/cbm/read.s
index 71ba5d713..fb0bb3171 100644
--- a/libsrc/cbm/read.s
+++ b/libsrc/cbm/read.s
@@ -135,7 +135,7 @@ eof:    lda     #0
 
 devnotpresent:
         lda     #ENODEV
-        .byte   $2C             ; Skip next opcode
+        jmp     __directerrno   ; Sets _errno, clears _oserror, returns -1
 
 ; Error entry: The given file descriptor is not valid or not open
 
diff --git a/libsrc/cbm/write.s b/libsrc/cbm/write.s
index 04010f2e4..ebc44a0ac 100644
--- a/libsrc/cbm/write.s
+++ b/libsrc/cbm/write.s
@@ -106,7 +106,7 @@ devnotpresent2:
         pla
 devnotpresent:
         lda     #ENODEV
-        .byte   $2C             ; Skip next opcode
+        jmp     __directerrno   ; Sets _errno, clears _oserror, returns -1
 
 ; Error entry: The given file descriptor is not valid or not open