diff --git a/src/sentry/rules/conditions/event_frequency.py b/src/sentry/rules/conditions/event_frequency.py
index f0adcbe6ea5555..5d6b1627ae0a9c 100644
--- a/src/sentry/rules/conditions/event_frequency.py
+++ b/src/sentry/rules/conditions/event_frequency.py
@@ -166,6 +166,8 @@ def passes(self, event: GroupEvent, state: EventState) -> bool:
 
         comparison_type = self.get_option("comparisonType", ComparisonType.COUNT)
         comparison_interval_option = self.get_option("comparisonInterval", "5m")
+        if comparison_interval_option == "":
+            return False
         comparison_interval = COMPARISON_INTERVALS[comparison_interval_option][1]
         _, duration = self.intervals[interval]
         try:
diff --git a/tests/snuba/rules/conditions/test_event_frequency.py b/tests/snuba/rules/conditions/test_event_frequency.py
index 319a204891c816..0e1f903db7389c 100644
--- a/tests/snuba/rules/conditions/test_event_frequency.py
+++ b/tests/snuba/rules/conditions/test_event_frequency.py
@@ -292,6 +292,15 @@ def _run_test(self, minutes, data, passes, add_events=False):
             self.assertDoesNotPass(rule, event, is_new=False)
             self.assertDoesNotPass(environment_rule, event, is_new=False)
 
+    def test_comparison_interval_empty_string(self):
+        data = {
+            "interval": "1m",
+            "value": 16,
+            "comparisonType": "count",
+            "comparisonInterval": "",
+        }
+        self._run_test(data=data, minutes=1, passes=False)
+
     def test_one_minute_with_events(self):
         data = {"interval": "1m", "value": 6, "comparisonType": "count", "comparisonInterval": "5m"}
         self._run_test(data=data, minutes=1, passes=True, add_events=True)