diff --git a/src/sentry/utils/performance_issues/detectors/http_overhead_detector.py b/src/sentry/utils/performance_issues/detectors/http_overhead_detector.py
index 7e4eb0f7f3b626..697a1e1a38d3f4 100644
--- a/src/sentry/utils/performance_issues/detectors/http_overhead_detector.py
+++ b/src/sentry/utils/performance_issues/detectors/http_overhead_detector.py
@@ -65,11 +65,13 @@ def visit_span(self, span: Span) -> None:
 
         url = span_data.get("url", "")
         span_start = span.get("start_timestamp", 0) * 1000
-        request_start = span_data.get("http.request.request_start", 0) * 1000
+        request_start = span_data.get("http.request.request_start", 0)
 
         if not url or not span_start or not request_start:
             return
 
+        request_start *= 1000
+
         if url.startswith("/"):
             location = "/"
         else:
diff --git a/tests/sentry/utils/performance_issues/test_http_overhead_detector.py b/tests/sentry/utils/performance_issues/test_http_overhead_detector.py
index 23fe84eecc0877..17175c8ecd3fe6 100644
--- a/tests/sentry/utils/performance_issues/test_http_overhead_detector.py
+++ b/tests/sentry/utils/performance_issues/test_http_overhead_detector.py
@@ -260,3 +260,23 @@ def test_detect_other_location(self):
                 evidence_display=[],
             )
         ]
+
+    def test_none_request_start(self):
+        url = "https://example.com/api/endpoint/123"
+        event = _valid_http_overhead_event("/api/endpoint/123")
+
+        # Include an invalid span to ensure it's not processed
+        span = create_span(
+            "http.client",
+            desc=url,
+            duration=1000,
+            data={
+                "url": url,
+                "network.protocol.version": "1.1",
+                "http.request.request_start": None,
+            },
+        )
+
+        event["spans"] = [span]
+
+        assert self.find_problems(event) == []