diff --git a/include/nlohmann/detail/exceptions.hpp b/include/nlohmann/detail/exceptions.hpp
index 96d7e0104..9f82d7f06 100644
--- a/include/nlohmann/detail/exceptions.hpp
+++ b/include/nlohmann/detail/exceptions.hpp
@@ -10,6 +10,9 @@
 
 #include <cstddef> // nullptr_t
 #include <exception> // exception
+#if JSON_DIAGNOSTICS
+    #include <numeric> // accumulate
+#endif
 #include <stdexcept> // runtime_error
 #include <string> // to_string
 #include <vector> // vector
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 83705f9f8..b04950bfb 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -183,6 +183,9 @@
 
 #include <cstddef> // nullptr_t
 #include <exception> // exception
+#if JSON_DIAGNOSTICS
+    #include <numeric> // accumulate
+#endif
 #include <stdexcept> // runtime_error
 #include <string> // to_string
 #include <vector> // vector