diff --git a/include/ncrypto.h b/include/ncrypto.h
index 49dbed3..d69b45b 100644
--- a/include/ncrypto.h
+++ b/include/ncrypto.h
@@ -12,13 +12,21 @@
 #include <openssl/ssl.h>
 #include <openssl/x509.h>
 
+#include <stdint.h>
 #include <cstddef>
+#include <cstdio>
 #include <functional>
 #include <list>
 #include <memory>
 #include <optional>
 #include <string>
 #include <string_view>
+#include <utility>
+
+#if NCRYPTO_DEVELOPMENT_CHECKS
+#include <iostream>
+#endif
+
 #ifndef OPENSSL_NO_ENGINE
 #include <openssl/engine.h>
 #endif  // !OPENSSL_NO_ENGINE
diff --git a/src/ncrypto.cpp b/src/ncrypto.cpp
index 75a28bb..60cfe6e 100644
--- a/src/ncrypto.cpp
+++ b/src/ncrypto.cpp
@@ -17,8 +17,12 @@
 
 #include <algorithm>
 #include <array>
+#include <cctype>
+#include <climits>
 #include <cstring>
 #include <string_view>
+#include <vector>
+
 #if OPENSSL_VERSION_MAJOR >= 3
 #include <openssl/core_names.h>
 #include <openssl/params.h>