diff --git a/backtracking/subarray_sum.cpp b/backtracking/subarray_sum.cpp
index 8001d74cc..fde1fe987 100644
--- a/backtracking/subarray_sum.cpp
+++ b/backtracking/subarray_sum.cpp
@@ -14,6 +14,7 @@
  */
 
 #include <cassert>        /// for assert
+#include <cstdint>        /// for integral typedefs
 #include <iostream>       /// for IO operations
 #include <unordered_map>  /// for unordered_map
 #include <vector>         /// for std::vector