diff --git a/cartographer/io/probability_grid_points_processor.cc b/cartographer/io/probability_grid_points_processor.cc
index 20f3bfb..12c856d 100644
--- a/cartographer/io/probability_grid_points_processor.cc
+++ b/cartographer/io/probability_grid_points_processor.cc
@@ -118,6 +118,9 @@ PointsProcessor::FlushResult ProbabilityGridPointsProcessor::Flush() {
       return FlushResult::kFinished;
   }
   LOG(FATAL);
+  // The following unreachable return statement is needed to avoid a GCC bug
+  // described at https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81508
+  return FlushResult::kFinished;
 }
 
 std::unique_ptr<Image> DrawProbabilityGrid(