diff --git a/src/catch2/catch_test_case_info.hpp b/src/catch2/catch_test_case_info.hpp
index ab5ae8b9..5ff3e3e7 100644
--- a/src/catch2/catch_test_case_info.hpp
+++ b/src/catch2/catch_test_case_info.hpp
@@ -15,6 +15,7 @@
 #include <catch2/internal/catch_unique_ptr.hpp>
 
 
+#include <cstdint>
 #include <string>
 #include <vector>
 
diff --git a/src/catch2/internal/catch_string_manip.hpp b/src/catch2/internal/catch_string_manip.hpp
index 8630b56a..dc0c552c 100644
--- a/src/catch2/internal/catch_string_manip.hpp
+++ b/src/catch2/internal/catch_string_manip.hpp
@@ -10,6 +10,7 @@
 
 #include <catch2/internal/catch_stringref.hpp>
 
+#include <cstdint>
 #include <string>
 #include <iosfwd>
 #include <vector>
diff --git a/src/catch2/internal/catch_xmlwriter.cpp b/src/catch2/internal/catch_xmlwriter.cpp
index d3bc6303..6c1d45df 100644
--- a/src/catch2/internal/catch_xmlwriter.cpp
+++ b/src/catch2/internal/catch_xmlwriter.cpp
@@ -11,6 +11,7 @@
 #include <catch2/internal/catch_enforce.hpp>
 #include <catch2/internal/catch_xmlwriter.hpp>
 
+#include <cstdint>
 #include <iomanip>
 #include <type_traits>