diff --git a/tests/emulator/common.py b/tests/emulator/common.py
index 52f94510..5f639a69 100644
--- a/tests/emulator/common.py
+++ b/tests/emulator/common.py
@@ -10,7 +10,7 @@
 
 def screenshot(d, suffix=''):
     os.makedirs('screenshots', exist_ok=True)
-    fname_base = f'screenshots/{time.time()}-{suffix}'
+    fname_base = f'screenshots/{time.time():.3f}-{suffix}'
     d.ui.screenshot(f'{fname_base}.png')
     with open(f'{fname_base}.xml', 'w') as f:
         f.write(d.ui.dump_hierarchy())