diff --git a/examples/07_ndjson.mojo b/examples/07_ndjson.mojo
index f29dfad..cf7491e 100644
--- a/examples/07_ndjson.mojo
+++ b/examples/07_ndjson.mojo
@@ -93,7 +93,7 @@ def main() raises:
     print()
 
     # Cleanup
-    import os
-    os.remove("example_data.ndjson")
+    import std.os
+    std.os.remove("example_data.ndjson")
 
     print("Done!")
diff --git a/tests/test_e2e.mojo b/tests/test_e2e.mojo
index ba24006..d3934a2 100644
--- a/tests/test_e2e.mojo
+++ b/tests/test_e2e.mojo
@@ -17,7 +17,7 @@ from json import loads, dumps, Value
 
 def _is_gpu_mode() -> Bool:
     var val = getenv("MOJSON_TEST_GPU")
-    return len(val) > 0 and val != "0" and val != "false"
+    return val.byte_length() > 0 and val != "0" and val != "false"
 
 
 def _test_loads(json: String) raises -> Value: