diff --git a/cores/esp32/FunctionalInterrupt.h b/cores/esp32/FunctionalInterrupt.h
index b5e3181f986..69bb5aee7b3 100644
--- a/cores/esp32/FunctionalInterrupt.h
+++ b/cores/esp32/FunctionalInterrupt.h
@@ -9,6 +9,7 @@
 #define CORE_CORE_FUNCTIONALINTERRUPT_H_
 
 #include <functional>
+#include <stdint.h>
 
 struct InterruptArgStructure {
 	std::function<void(void)> interruptFunction;