diff --git a/src/include/private/base64.h b/src/include/private/base64.h
index 3f0dc68..1a6d2d5 100644
--- a/src/include/private/base64.h
+++ b/src/include/private/base64.h
@@ -22,6 +22,7 @@
 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 #ifndef SRC_INCLUDE_PRIVATE_BASE64_H_
 #define SRC_INCLUDE_PRIVATE_BASE64_H_
+#include <cstdint>
 #include <math.h>
 #include <string>