diff --git a/src/json.hpp b/src/json.hpp
index ba7d82122..44c867c08 100644
--- a/src/json.hpp
+++ b/src/json.hpp
@@ -37,6 +37,7 @@ SOFTWARE.
 #include <cmath>
 #include <cstddef>
 #include <cstdio>
+#include <cstdint>
 #include <cstdlib>
 #include <functional>
 #include <initializer_list>
diff --git a/src/json.hpp.re2c b/src/json.hpp.re2c
index 5ee270f91..dffce54c9 100644
--- a/src/json.hpp.re2c
+++ b/src/json.hpp.re2c
@@ -37,6 +37,7 @@ SOFTWARE.
 #include <cmath>
 #include <cstddef>
 #include <cstdio>
+#include <cstdint>
 #include <cstdlib>
 #include <functional>
 #include <initializer_list>