diff --git a/image/fastboot.py b/image/fastboot.py
index d8816bf..937b348 100644
--- a/image/fastboot.py
+++ b/image/fastboot.py
@@ -1,12 +1,12 @@
 import logging
-import subprocess
 
+from exec.cmd import run_cmd, CompletedProcess
 from typing import Optional
 
 
 def fastboot_erase_dtbo():
     logging.info("Fastboot: Erasing DTBO")
-    subprocess.run(
+    run_cmd(
         [
             'fastboot',
             'erase',
@@ -18,23 +18,25 @@ def fastboot_erase_dtbo():
 
 def fastboot_flash(partition: str, file: str, sparse_size: Optional[str] = None):
     logging.info(f"Fastboot: Flashing {file} to {partition}")
-    result = subprocess.run([
+    result = run_cmd([
         'fastboot',
         *(['-S', sparse_size] if sparse_size is not None else []),
         'flash',
         partition,
         file,
     ])
+    assert isinstance(result, CompletedProcess)
     if result.returncode != 0:
         raise Exception(f'Failed to flash {file}')
 
 
 def fastboot_boot(file):
     logging.info(f"Fastboot: booting {file}")
-    result = subprocess.run([
+    result = run_cmd([
         'fastboot',
         'boot',
         file,
     ])
+    assert isinstance(result, CompletedProcess)
     if result.returncode != 0:
         raise Exception(f'Failed to boot {file} using fastboot')