diff --git a/modules/congestion_controller/goog_cc/link_capacity_estimator.cc b/modules/congestion_controller/goog_cc/link_capacity_estimator.cc
index d16f074..8f59c9a 100644
--- a/modules/congestion_controller/goog_cc/link_capacity_estimator.cc
+++ b/modules/congestion_controller/goog_cc/link_capacity_estimator.cc
@@ -25,8 +25,8 @@
 
 DataRate LinkCapacityEstimator::LowerBound() const {
   if (estimate_kbps_.has_value())
-    return DataRate::kbps(estimate_kbps_.value() -
-                          3 * deviation_estimate_kbps());
+    return DataRate::kbps(
+        std::max(0.0, estimate_kbps_.value() - 3 * deviation_estimate_kbps()));
   return DataRate::Zero();
 }