1 files changed, 10 insertions, 0 deletions
diff --git a/src/fs.asm b/src/fs.asm
index d543b0f..a4ad77e 100644
--- a/src/fs.asm
+++ b/src/fs.asm
@@ -678,6 +678,13 @@ sys_open::
     ld [wFsDir], a
     call dir_find               ; A = target inode or 0
     ld [wFsInode], a
+    or a
+    jr z, .notdir               ; doesn't exist yet: no type to check
+    call inode_ptr
+    ld a, [hl]                  ; I_TYPE
+    cp IT_DIR
+    jr z, .isdir                ; can't open a directory as a file
+.notdir
     ld a, [wFsMode]
     or a
     jr nz, .write
@@ -730,6 +737,9 @@ sys_open::
     ld a, c
     cp OF_MAX
     jr c, .ofl
+.isdir
+    ld a, $FE                   ; EISDIR: is a directory
+    ret
 .fail
     ld a, $FF
     ret