diff --git a/main.cpp b/main.cpp
index af2fd235..5f2760f9 100644
--- a/main.cpp
+++ b/main.cpp
@@ -68,7 +68,7 @@ static int min_detail = 7;
 int quiet = 0;
 int quiet_progress = 0;
 double progress_interval = 0;
-volatile double last_progress = 0;
+std::atomic<double> last_progress(0);
 int geometry_scale = 0;
 double simplification = 1;
 size_t max_tile_size = 500000;
diff --git a/main.hpp b/main.hpp
index 7e3c6475..9a74a921 100644
--- a/main.hpp
+++ b/main.hpp
@@ -2,6 +2,7 @@
 #define MAIN_HPP
 
 #include <stddef.h>
+#include <atomic>
 
 struct index {
 	long long start = 0;
@@ -23,7 +24,7 @@ extern int geometry_scale;
 extern int quiet;
 extern int quiet_progress;
 extern double progress_interval;
-extern volatile double last_progress;
+extern std::atomic<double> last_progress;
 
 extern size_t CPUS;
 extern size_t TEMP_FILES;