diff --git a/shell.c b/shell.c
index 05595be..d803163 100644
--- a/shell.c
+++ b/shell.c
@@ -1248,7 +1248,12 @@ shell_blit_bitmap(int argc, char **argv) {
         fputs(usage, fout);
         return;
     }
-    FILE *f = fopen(argv[1], "r");
+    const char *fname = argv[1];
+    FILE *f = fopen(fname, "r");
+    if (!f) {
+        fprintf(fout, "[!] can't open file '%s': %s\n", fname, strerror(errno));
+        return;
+    }
     fseek(f, 0, SEEK_END);
     size_t fsize = ftell(f);
     rewind(f);
diff --git a/test/chess_image.rgba b/test/chess_image.rgba
new file mode 100644
index 0000000..fd1dbcf
Binary files /dev/null and b/test/chess_image.rgba differ
diff --git a/umka.asm b/umka.asm
index 11a3265..1d4d2e2 100644
--- a/umka.asm
+++ b/umka.asm
@@ -130,7 +130,6 @@ BTN_BUFF equ __pew15
 BTN_ADDR equ __pew16
 MEM_AMOUNT equ __pew17
 SYS_SHUTDOWN equ __pew18
-;TASK_COUNT equ __pew19
 SLOT_BASE equ __pew20
 sys_proc equ __pew21
 VGABasePtr equ __pew22
@@ -145,7 +144,6 @@ restore TASK_BASE,TASK_DATA,TASK_EVENT,CDDataBuf,idts,WIN_STACK,WIN_POS
 restore FDD_BUFF,WIN_TEMP_XY,KEY_COUNT,KEY_BUFF,BTN_COUNT,BTN_BUFF,BTN_ADDR
 restore MEM_AMOUNT,SYS_SHUTDOWN,SLOT_BASE,sys_proc,VGABasePtr
 restore HEAP_BASE
-;restore TASK_COUNT
 purge BOOT_LO,BOOT
 
 LFB_BASE = lfb_base
@@ -698,14 +696,6 @@ macro lea r, v {
   end if
 }
 
-;macro mov r, v {
-;  if v eq (HEAP_BASE-OS_BASE-CLEAN_ZONE) / 4
-;        int3
-;  else
-;        mov     r, v
-;  end if
-;}
-
 include 'kernel.asm'
 
 purge lea,add,org,mov