diff --git a/src/stim/util_bot/probability_util.cc b/src/stim/util_bot/probability_util.cc
index 2b66c0857..2bf1487cb 100644
--- a/src/stim/util_bot/probability_util.cc
+++ b/src/stim/util_bot/probability_util.cc
@@ -14,6 +14,7 @@
 
 #include "stim/util_bot/probability_util.h"
 
+#include <cmath>
 #include <cstring>
 
 #include "stim/util_bot/arg_parse.h"