diff --git a/lifting/importers.py b/lifting/importers.py
index 1809016..f373803 100644
--- a/lifting/importers.py
+++ b/lifting/importers.py
@@ -1,4 +1,5 @@
 import sqlite3
+from django.db import transaction
 from lifting.models import Exercise, Set
 
 
@@ -23,16 +24,17 @@ def import_fitnotes_db(filename):
         # map to an Exercise id or str
         exercise_id_mapping[fnid] = exercises[cleaned] if cleaned in exercises else cleaned
 
-    Set.objects.filter(source='fitnotes').delete()
-    for fnid, date, weight_kg, reps in cur.execute(
-        'SELECT exercise_id, date, metric_weight, reps FROM training_log'):
+    with transaction.atomic():
+        Set.objects.filter(source='fitnotes').delete()
+        for fnid, date, weight_kg, reps in cur.execute(
+            'SELECT exercise_id, date, metric_weight, reps FROM training_log'):
 
-        # create Exercise if it wasn't found and there's a workout using it
-        if isinstance(exercise_id_mapping[fnid], str):
-            exercise_id_mapping[fnid] = Exercise.objects.create(
-                names=[exercise_id_mapping[fnid]]).id
+            # create Exercise if it wasn't found and there's a workout using it
+            if isinstance(exercise_id_mapping[fnid], str):
+                exercise_id_mapping[fnid] = Exercise.objects.create(
+                    names=[exercise_id_mapping[fnid]]).id
 
-        exercise_id = exercise_id_mapping[fnid]
+            exercise_id = exercise_id_mapping[fnid]
 
-        Set.objects.create(exercise_id=exercise_id, date=date, weight_kg=weight_kg, reps=reps,
-                           source='fitnotes')
+            Set.objects.create(exercise_id=exercise_id, date=date, weight_kg=weight_kg, reps=reps,
+                            source='fitnotes')
diff --git a/lifting/testdata/baddata.fitnotes b/lifting/testdata/baddata.fitnotes
new file mode 100644
index 0000000..a0de8a8
Binary files /dev/null and b/lifting/testdata/baddata.fitnotes differ
diff --git a/lifting/tests.py b/lifting/tests.py
index 1892aa8..a82af2d 100644
--- a/lifting/tests.py
+++ b/lifting/tests.py
@@ -32,3 +32,14 @@ class TestFitnotesImport(TestCase):
         import_fitnotes_db('lifting/testdata/example.fitnotes')
         assert Exercise.objects.count() == 2
         assert Set.objects.count() == 9
+
+    def test_bad_import(self):
+        # good db then bad db, should fail without screwing up existing data
+        import_fitnotes_db('lifting/testdata/example.fitnotes')
+        try:
+            # baddata.fitnotes has all exercise ids set to 9999
+            import_fitnotes_db('lifting/testdata/baddata.fitnotes')
+        except Exception:
+            pass
+        assert Exercise.objects.count() == 2
+        assert Set.objects.count() == 9