diff --git a/tests/it.py b/tests/it.py
index 8b6fa89..a9b848b 100755
--- a/tests/it.py
+++ b/tests/it.py
@@ -17,8 +17,19 @@
 # SPDX-License-Identifier: Apache-2.0
 
 from pathlib import Path
+import difflib
 import subprocess
 
+def diff_files(file1, file2):
+    with file1.open("r") as f1, file2.open("r") as f2:
+        diff = difflib.unified_diff(f1.readlines(), f2.readlines(), str(file1), str(file2))
+        diff = list(diff)
+        if diff:
+            for line in diff:
+                print(line, end="")
+            exit(1)
+
+
 basedir = Path(__file__).parent.absolute()
 rootdir = basedir.parent
 
@@ -26,7 +37,7 @@
 hawkeye = rootdir / "target" / "debug" / "hawkeye"
 
 subprocess.run([hawkeye, "format", "--fail-if-unknown", "--fail-if-updated=false", "--dry-run"], cwd=(basedir / "load_header_path"), check=True)
-subprocess.run(["diff", "main.rs.expected", "main.rs.formatted"], cwd=(basedir / "load_header_path"), check=True)
+diff_files(basedir / "load_header_path" / "main.rs.expected", basedir / "load_header_path" / "main.rs.formatted")
 
 subprocess.run([hawkeye, "format", "--fail-if-unknown", "--fail-if-updated=false", "--dry-run"], cwd=(basedir / "regression_blank_line"), check=True)
-subprocess.run(["diff", "main.rs.expected", "main.rs.formatted"], cwd=(basedir / "regression_blank_line"), check=True)
+diff_files(basedir / "regression_blank_line" / "main.rs.expected", basedir / "regression_blank_line" / "main.rs.formatted")