diff --git a/CMakeLists.txt b/CMakeLists.txt
index f84d4b77..ec5f74fd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -141,7 +141,7 @@ check_include_files(inttypes.h HAVE_INTTYPES_H)
 if(NOT MSVC)
   check_include_files(unistd.h HAVE_UNISTD_H)
   check_include_files(sys/time.h HAVE_SYS_TIME_H)
-  check_include_files(sys/param.h HAVE_SYS_PARAM_H)
+  check_include_files(sys/param.h HAVE_SYS_PARAM_H)  # tests
 endif()
 if(NOT WIN32)
   check_include_files(sys/select.h HAVE_SYS_SELECT_H)
diff --git a/example/direct_tcpip.c b/example/direct_tcpip.c
index 1d9b041a..46d21e90 100644
--- a/example/direct_tcpip.c
+++ b/example/direct_tcpip.c
@@ -10,9 +10,6 @@
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
@@ -23,11 +20,9 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 #ifndef INADDR_NONE
 #define INADDR_NONE (in_addr_t)~0
diff --git a/example/scp.c b/example/scp.c
index 2c0e0af6..a80c5124 100644
--- a/example/scp.c
+++ b/example/scp.c
@@ -22,11 +22,7 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <ctype.h>
 
 static const char *pubkey = "/home/username/.ssh/id_rsa.pub";
 static const char *privkey = "/home/username/.ssh/id_rsa";
diff --git a/example/scp_nonblock.c b/example/scp_nonblock.c
index 615b4ea5..13951dc6 100644
--- a/example/scp_nonblock.c
+++ b/example/scp_nonblock.c
@@ -17,9 +17,6 @@
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
@@ -33,11 +30,7 @@
 #include <sys/time.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <ctype.h>
 
 static const char *pubkey = "/home/username/.ssh/id_rsa.pub";
 static const char *privkey = "/home/username/.ssh/id_rsa";
diff --git a/example/scp_write.c b/example/scp_write.c
index 7da38ac7..7390548d 100644
--- a/example/scp_write.c
+++ b/example/scp_write.c
@@ -18,11 +18,7 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <ctype.h>
 
 static const char *pubkey = "/home/username/.ssh/id_rsa.pub";
 static const char *privkey = "/home/username/.ssh/id_rsa";
diff --git a/example/scp_write_nonblock.c b/example/scp_write_nonblock.c
index 996778cb..29ff08bd 100644
--- a/example/scp_write_nonblock.c
+++ b/example/scp_write_nonblock.c
@@ -8,9 +8,6 @@
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
@@ -21,12 +18,8 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <ctype.h>
-#include <time.h>
+#include <time.h>  /* for time() */
 
 static const char *pubkey = "/home/username/.ssh/id_rsa.pub";
 static const char *privkey = "/home/username/.ssh/id_rsa";
diff --git a/example/sftp.c b/example/sftp.c
index 3a3c5866..c85012bc 100644
--- a/example/sftp.c
+++ b/example/sftp.c
@@ -28,11 +28,8 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <ctype.h>
+#include <string.h>
 
 static const char *pubkey = "/home/username/.ssh/id_rsa.pub";
 static const char *privkey = "/home/username/.ssh/id_rsa";
diff --git a/example/sftp_RW_nonblock.c b/example/sftp_RW_nonblock.c
index 61dda867..25f02a31 100644
--- a/example/sftp_RW_nonblock.c
+++ b/example/sftp_RW_nonblock.c
@@ -18,9 +18,6 @@
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
@@ -28,11 +25,7 @@
 #include <netinet/in.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <ctype.h>
 
 static const char *pubkey = "/home/username/.ssh/id_rsa.pub";
 static const char *privkey = "/home/username/.ssh/id_rsa";
diff --git a/example/sftp_append.c b/example/sftp_append.c
index 6793ccb7..60ced4f3 100644
--- a/example/sftp_append.c
+++ b/example/sftp_append.c
@@ -24,11 +24,7 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <ctype.h>
 
 static const char *pubkey = "/home/username/.ssh/id_rsa.pub";
 static const char *privkey = "/home/username/.ssh/id_rsa";
diff --git a/example/sftp_mkdir.c b/example/sftp_mkdir.c
index 3937d5be..2edfcba2 100644
--- a/example/sftp_mkdir.c
+++ b/example/sftp_mkdir.c
@@ -24,11 +24,7 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <ctype.h>
 
 static const char *pubkey = "/home/username/.ssh/id_rsa.pub";
 static const char *privkey = "/home/username/.ssh/id_rsa";
diff --git a/example/sftp_mkdir_nonblock.c b/example/sftp_mkdir_nonblock.c
index acbec2b4..b9902372 100644
--- a/example/sftp_mkdir_nonblock.c
+++ b/example/sftp_mkdir_nonblock.c
@@ -24,11 +24,7 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <ctype.h>
 
 static const char *pubkey = "/home/username/.ssh/id_rsa.pub";
 static const char *privkey = "/home/username/.ssh/id_rsa";
diff --git a/example/sftp_nonblock.c b/example/sftp_nonblock.c
index b44574c4..19685aca 100644
--- a/example/sftp_nonblock.c
+++ b/example/sftp_nonblock.c
@@ -18,9 +18,6 @@
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
@@ -34,11 +31,7 @@
 #include <sys/time.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <ctype.h>
 
 static const char *pubkey = "/home/username/.ssh/id_rsa.pub";
 static const char *privkey = "/home/username/.ssh/id_rsa";
diff --git a/example/sftp_write.c b/example/sftp_write.c
index b2169e40..85818a71 100644
--- a/example/sftp_write.c
+++ b/example/sftp_write.c
@@ -24,11 +24,7 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <ctype.h>
 
 static const char *pubkey = "/home/username/.ssh/id_rsa.pub";
 static const char *privkey = "/home/username/.ssh/id_rsa";
diff --git a/example/sftp_write_nonblock.c b/example/sftp_write_nonblock.c
index 602a780c..4570318d 100644
--- a/example/sftp_write_nonblock.c
+++ b/example/sftp_write_nonblock.c
@@ -14,9 +14,6 @@
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
@@ -27,12 +24,8 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <ctype.h>
-#include <time.h>
+#include <time.h>  /* for time() */
 
 static const char *pubkey = "/home/username/.ssh/id_rsa.pub";
 static const char *privkey = "/home/username/.ssh/id_rsa";
diff --git a/example/sftp_write_sliding.c b/example/sftp_write_sliding.c
index b1b7972b..f6f2b33b 100644
--- a/example/sftp_write_sliding.c
+++ b/example/sftp_write_sliding.c
@@ -14,9 +14,6 @@
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
@@ -27,12 +24,9 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <ctype.h>
-#include <time.h>
+#include <time.h>  /* for time() */
+#include <string.h>
 
 static const char *pubkey = "/home/username/.ssh/id_rsa.pub";
 static const char *privkey = "/home/username/.ssh/id_rsa";
diff --git a/example/sftpdir.c b/example/sftpdir.c
index 655db525..8d9bd3d9 100644
--- a/example/sftpdir.c
+++ b/example/sftpdir.c
@@ -24,11 +24,8 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <ctype.h>
+#include <string.h>
 
 #if defined(_MSC_VER)
 #define __FILESIZE "I64u"
diff --git a/example/sftpdir_nonblock.c b/example/sftpdir_nonblock.c
index 8237f6a7..ca12e625 100644
--- a/example/sftpdir_nonblock.c
+++ b/example/sftpdir_nonblock.c
@@ -24,11 +24,7 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <ctype.h>
 
 #if defined(_MSC_VER)
 #define __FILESIZE "I64u"
diff --git a/example/ssh2.c b/example/ssh2.c
index 6267244e..26f15cfe 100644
--- a/example/ssh2.c
+++ b/example/ssh2.c
@@ -28,12 +28,9 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <ctype.h>
+#include <string.h>
 
 #if defined(_MSC_VER) && _MSC_VER < 1900
 #define snprintf _snprintf
diff --git a/example/ssh2_agent.c b/example/ssh2_agent.c
index 6ad76313..9c7997d1 100644
--- a/example/ssh2_agent.c
+++ b/example/ssh2_agent.c
@@ -22,12 +22,8 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <stdlib.h>
-#include <ctype.h>
+#include <string.h>
 
 static const char *username = "username";
 
diff --git a/example/ssh2_agent_forwarding.c b/example/ssh2_agent_forwarding.c
index 047920c9..c12c1989 100644
--- a/example/ssh2_agent_forwarding.c
+++ b/example/ssh2_agent_forwarding.c
@@ -17,9 +17,6 @@
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
@@ -30,12 +27,8 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <ctype.h>
 
 static const char *hostname = "127.0.0.1";
 static const char *commandline = "uptime";
diff --git a/example/ssh2_echo.c b/example/ssh2_echo.c
index 1fa87b7a..70115fed 100644
--- a/example/ssh2_echo.c
+++ b/example/ssh2_echo.c
@@ -12,9 +12,6 @@
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
@@ -25,12 +22,9 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <ctype.h>
+#include <string.h>
 
 static const char *hostname = "127.0.0.1";
 static const char *commandline = "cat";
diff --git a/example/ssh2_exec.c b/example/ssh2_exec.c
index d180f62d..c39421fc 100644
--- a/example/ssh2_exec.c
+++ b/example/ssh2_exec.c
@@ -14,9 +14,6 @@
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
@@ -27,12 +24,9 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <ctype.h>
+#include <string.h>
 
 static const char *hostname = "127.0.0.1";
 static const char *commandline = "uptime";
diff --git a/example/subsystem_netconf.c b/example/subsystem_netconf.c
index fd24039f..7029fb8d 100644
--- a/example/subsystem_netconf.c
+++ b/example/subsystem_netconf.c
@@ -14,11 +14,7 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
 
 #ifndef INADDR_NONE
diff --git a/example/tcpip-forward.c b/example/tcpip-forward.c
index a0b1cd69..156075bb 100644
--- a/example/tcpip-forward.c
+++ b/example/tcpip-forward.c
@@ -10,9 +10,6 @@
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
@@ -23,11 +20,9 @@
 #include <arpa/inet.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 #ifndef INADDR_NONE
 #define INADDR_NONE (in_addr_t)~0
diff --git a/example/x11.c b/example/x11.c
index 6254519f..fce07771 100644
--- a/example/x11.c
+++ b/example/x11.c
@@ -20,9 +20,6 @@
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef HAVE_SYS_SELECT_H
-#include <sys/select.h>
-#endif
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
@@ -33,11 +30,7 @@
 #include <sys/un.h>
 #endif
 
-#include <sys/types.h>
-#include <fcntl.h>
-#include <errno.h>
 #include <stdlib.h>
-#include <ctype.h>
 #include <string.h>
 
 #include <termios.h>
diff --git a/include/libssh2.h b/include/libssh2.h
index 28698317..e13e2f13 100644
--- a/include/libssh2.h
+++ b/include/libssh2.h
@@ -185,8 +185,6 @@ typedef int libssh2_socket_t;
 
 #ifdef LIBSSH2_USE_WIN32_LARGE_FILES
 #  include <io.h>
-#  include <sys/types.h>
-#  include <sys/stat.h>
 #  define LIBSSH2_STRUCT_STAT_SIZE_FORMAT    "%I64d"
 typedef struct _stati64 libssh2_struct_stat;
 typedef __int64 libssh2_struct_stat_size;
@@ -197,8 +195,6 @@ typedef __int64 libssh2_struct_stat_size;
  */
 
 #ifdef LIBSSH2_USE_WIN32_SMALL_FILES
-#  include <sys/types.h>
-#  include <sys/stat.h>
 #  ifndef _WIN32_WCE
 #    define LIBSSH2_STRUCT_STAT_SIZE_FORMAT    "%d"
 typedef struct _stat libssh2_struct_stat;
diff --git a/src/agent.c b/src/agent.c
index cb1fe20b..76308f7d 100644
--- a/src/agent.c
+++ b/src/agent.c
@@ -39,7 +39,10 @@
 
 #include "libssh2_priv.h"
 #include "agent.h"
+
 #include <errno.h>
+#include <stdlib.h>  /* for getenv() */
+
 #ifdef HAVE_SYS_UN_H
 #include <sys/un.h>
 #else
@@ -48,6 +51,7 @@
    support them. */
 #undef PF_UNIX
 #endif
+
 #include "userauth.h"
 #include "session.h"
 
diff --git a/src/agent_win.c b/src/agent_win.c
index 4a93e1ca..b735e102 100644
--- a/src/agent_win.c
+++ b/src/agent_win.c
@@ -39,7 +39,6 @@
 
 #include "libssh2_priv.h"
 #include "agent.h"
-#include <errno.h>
 
 #if defined(WIN32) && !defined(LIBSSH2_WINDOWS_UWP)
 
diff --git a/src/bcrypt_pbkdf.c b/src/bcrypt_pbkdf.c
index 5382c0bd..91be901c 100644
--- a/src/bcrypt_pbkdf.c
+++ b/src/bcrypt_pbkdf.c
@@ -20,10 +20,6 @@
 #ifndef HAVE_BCRYPT_PBKDF
 
 #include <stdlib.h>
-#include <sys/types.h>
-#ifdef HAVE_SYS_PARAM_H
-#include <sys/param.h>
-#endif
 
 #define LIBSSH2_BCRYPT_PBKDF_C
 #include "blowfish.c"
diff --git a/src/channel.c b/src/channel.c
index cf094298..06a6acae 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -39,13 +39,14 @@
  */
 
 #include "libssh2_priv.h"
+
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
-#include <fcntl.h>
 #ifdef HAVE_INTTYPES_H
 #include <inttypes.h>
 #endif
+
 #include <assert.h>
 
 #include "channel.h"
diff --git a/src/comp.c b/src/comp.c
index 527c516a..f3565056 100644
--- a/src/comp.c
+++ b/src/comp.c
@@ -37,6 +37,7 @@
  */
 
 #include "libssh2_priv.h"
+
 #ifdef LIBSSH2_HAVE_ZLIB
 #include <zlib.h>
 #undef compress /* dodge name clash with ZLIB macro */
diff --git a/src/libgcrypt.c b/src/libgcrypt.c
index ccee5834..55d971b6 100644
--- a/src/libgcrypt.c
+++ b/src/libgcrypt.c
@@ -38,8 +38,6 @@
 
 #ifdef LIBSSH2_CRYPTO_C /* Compile this via crypto.c */
 
-#include <string.h>
-
 #if LIBSSH2_RSA
 int
 _libssh2_rsa_new(libssh2_rsa_ctx ** rsa,
diff --git a/src/libssh2_priv.h b/src/libssh2_priv.h
index 857b1359..82c3afe2 100644
--- a/src/libssh2_priv.h
+++ b/src/libssh2_priv.h
@@ -47,6 +47,7 @@
 #include "libssh2_setup.h"
 
 #include <stdio.h>
+#include <string.h>
 #include <time.h>
 #include <limits.h>
 
@@ -59,14 +60,8 @@
 */
 #ifdef HAVE_POLL
 # include <poll.h>
-#else
-# if defined(HAVE_SELECT) && !defined(WIN32)
-# ifdef HAVE_SYS_SELECT_H
-#  include <sys/select.h>
-# else
-#  include <sys/types.h>
-# endif
-# endif
+#elif defined(HAVE_SELECT) && defined(HAVE_SYS_SELECT_H)
+# include <sys/select.h>
 #endif
 
 /* Needed for struct iovec on some platforms */
@@ -914,14 +909,6 @@ struct _LIBSSH2_SESSION
     long packet_read_timeout;
 };
 
-#if defined(HAVE_STRTOLL)
-#define scpsize_strtol strtoll
-#elif defined(HAVE_STRTOI64)
-#define scpsize_strtol _strtoi64
-#else
-#define scpsize_strtol strtol
-#endif
-
 /* session.state bits */
 #define LIBSSH2_STATE_EXCHANGING_KEYS   0x00000001
 #define LIBSSH2_STATE_NEWKEYS           0x00000002
diff --git a/src/mbedtls.c b/src/mbedtls.c
index c7d0b56b..4a441cba 100644
--- a/src/mbedtls.c
+++ b/src/mbedtls.c
@@ -37,6 +37,8 @@
 
 #ifdef LIBSSH2_CRYPTO_C /* Compile this via crypto.c */
 
+#include <stdlib.h>
+
 #if MBEDTLS_VERSION_NUMBER < 0x03000000
 #define mbedtls_cipher_info_get_key_bitlen(c) (c->key_bitlen)
 #define mbedtls_cipher_info_get_iv_size(c)    (c->iv_size)
diff --git a/src/mbedtls.h b/src/mbedtls.h
index 80658440..80a051ed 100644
--- a/src/mbedtls.h
+++ b/src/mbedtls.h
@@ -39,9 +39,6 @@
 
 #define LIBSSH2_CRYPTO_ENGINE libssh2_mbedtls
 
-#include <stdlib.h>
-#include <string.h>
-
 #include <mbedtls/platform.h>
 #include <mbedtls/md.h>
 #include <mbedtls/rsa.h>
@@ -162,6 +159,7 @@
 #define libssh2_sha1(data, datalen, hash) \
     _libssh2_mbedtls_hash(data, datalen, MBEDTLS_MD_SHA1, hash)
 
+
 /*******************************************************************/
 /*
  * mbedTLS backend: SHA256 functions
diff --git a/src/misc.c b/src/misc.c
index 8151eab7..10864b8b 100644
--- a/src/misc.c
+++ b/src/misc.c
@@ -40,21 +40,18 @@
 #include "libssh2_priv.h"
 #include "misc.h"
 
-#include <stdlib.h>
-
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
 
+#include <errno.h>
+
 #ifdef WIN32
 /* Force parameter type. */
 #define recv(s, b, l, f)  recv((s), (b), (int)(l), (f))
 #define send(s, b, l, f)  send((s), (b), (int)(l), (f))
 #endif
 
-#include <stdio.h>
-#include <errno.h>
-
 /* snprintf not in Visual Studio CRT and _snprintf dangerously incompatible.
    We provide a safe wrapper if snprintf not found */
 #ifdef LIBSSH2_SNPRINTF
diff --git a/src/openssl.c b/src/openssl.c
index 590b28cc..89560efc 100644
--- a/src/openssl.c
+++ b/src/openssl.c
@@ -40,8 +40,8 @@
 
 #ifdef LIBSSH2_CRYPTO_C /* Compile this via crypto.c */
 
+#include <stdlib.h>
 #include <assert.h>
-#include <string.h>
 
 #ifndef EVP_MAX_BLOCK_LENGTH
 #define EVP_MAX_BLOCK_LENGTH 32
diff --git a/src/os400qc3.c b/src/os400qc3.c
index 870b5100..ed7e8f6e 100644
--- a/src/os400qc3.c
+++ b/src/os400qc3.c
@@ -41,7 +41,6 @@
 
 #include <stdlib.h>
 
-#include <stdio.h>
 #include <stdarg.h>
 #include <alloca.h>
 #include <sys/uio.h>
diff --git a/src/packet.c b/src/packet.c
index 9023f3bf..8c8e6675 100644
--- a/src/packet.c
+++ b/src/packet.c
@@ -39,24 +39,18 @@
  */
 
 #include "libssh2_priv.h"
-#include <errno.h>
-#include <fcntl.h>
 
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
-
 #ifdef HAVE_INTTYPES_H
 #include <inttypes.h>
 #endif
-
 /* Needed for struct iovec on some platforms */
 #ifdef HAVE_SYS_UIO_H
 #include <sys/uio.h>
 #endif
 
-#include <sys/types.h>
-
 #include "transport.h"
 #include "channel.h"
 #include "packet.h"
diff --git a/src/scp.c b/src/scp.c
index b68cb8e3..b829dad8 100644
--- a/src/scp.c
+++ b/src/scp.c
@@ -37,12 +37,19 @@
  */
 
 #include "libssh2_priv.h"
-#include <errno.h>
-#include <stdlib.h>
 
 #include "channel.h"
 #include "session.h"
 
+#include <stdlib.h>  /* strtoll(), _strtoi64(), strtol() */
+
+#if defined(HAVE_STRTOLL)
+#define scpsize_strtol strtoll
+#elif defined(HAVE_STRTOI64)
+#define scpsize_strtol _strtoi64
+#else
+#define scpsize_strtol strtol
+#endif
 
 /* Max. length of a quoted string after libssh2_shell_quotearg() processing */
 #define _libssh2_shell_quotedsize(s)     (3 * strlen(s) + 2)
diff --git a/src/session.c b/src/session.c
index 7b1f6828..a4d602ba 100644
--- a/src/session.c
+++ b/src/session.c
@@ -42,18 +42,17 @@
 #ifdef WIN32
 #include <ws2tcpip.h>  /* for socklen_t */
 #endif
-
-#include <errno.h>
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
-#include <stdlib.h>
-#include <fcntl.h>
-
 #ifdef HAVE_ALLOCA_H
 #include <alloca.h>
 #endif
 
+#include <errno.h>
+#include <stdlib.h>
+#include <fcntl.h>
+
 #include "transport.h"
 #include "session.h"
 #include "channel.h"
diff --git a/src/sftp.c b/src/sftp.c
index 6f577378..1da891e2 100644
--- a/src/sftp.c
+++ b/src/sftp.c
@@ -37,14 +37,15 @@
  * OF SUCH DAMAGE.
  */
 
-#include <assert.h>
-
 #include "libssh2_priv.h"
 #include "libssh2_sftp.h"
+
 #include "channel.h"
 #include "session.h"
 #include "sftp.h"
 
+#include <assert.h>
+
 /* This release of libssh2 implements Version 5 with automatic downgrade
  * based on server's declaration
  *   https://www.ietf.org/archive/id/draft-ietf-secsh-filexfer-05.txt
diff --git a/src/transport.c b/src/transport.c
index bce6413d..4eeceab3 100644
--- a/src/transport.c
+++ b/src/transport.c
@@ -39,13 +39,9 @@
  */
 
 #include "libssh2_priv.h"
-#include <errno.h>
-#include <fcntl.h>
-#include <ctype.h>
-#ifdef LIBSSH2DEBUG
-#include <stdio.h>
-#endif
 
+#include <errno.h>
+#include <ctype.h>
 #include <assert.h>
 
 #include "transport.h"
diff --git a/src/userauth.c b/src/userauth.c
index a1c62f69..78b511cc 100644
--- a/src/userauth.c
+++ b/src/userauth.c
@@ -40,9 +40,6 @@
 #include "libssh2_priv.h"
 
 #include <ctype.h>
-#include <stdio.h>
-
-#include <assert.h>
 
 /* Needed for struct iovec on some platforms */
 #ifdef HAVE_SYS_UIO_H
diff --git a/tests/openssh_fixture.c b/tests/openssh_fixture.c
index cbe08d99..5eab3433 100644
--- a/tests/openssh_fixture.c
+++ b/tests/openssh_fixture.c
@@ -41,19 +41,20 @@
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 #ifdef HAVE_ARPA_INET_H
 #include <arpa/inet.h>
 #endif
 #ifdef HAVE_NETINET_IN_H
 #include <netinet/in.h>
 #endif
-#ifdef HAVE_UNISTD_H
-#include <unistd.h>
-#endif
-#include <ctype.h>
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>
+#include <ctype.h>
 
 #if defined(WIN32) && defined(_WIN64)
 #define LIBSSH2_SOCKET_MASK "%lld"
diff --git a/tests/session_fixture.c b/tests/session_fixture.c
index 153083e8..922a442b 100644
--- a/tests/session_fixture.c
+++ b/tests/session_fixture.c
@@ -38,25 +38,25 @@
 #include "session_fixture.h"
 #include "openssh_fixture.h"
 
-#include <stdio.h>
-#include <stdlib.h>
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
+#ifdef HAVE_SYS_PARAM_H
+#include <sys/param.h>
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
 
 #ifdef _MSC_VER
 #include <direct.h>
 #define chdir _chdir
 #endif
 
-#ifdef HAVE_SYS_SOCKET_H
-#include <sys/socket.h>
-#endif
-#ifdef HAVE_SYS_PARAM_H
-#include <sys/param.h>
-#endif
-#include <assert.h>
-
 static LIBSSH2_SESSION *connected_session = NULL;
 static libssh2_socket_t connected_socket = LIBSSH2_INVALID_SOCKET;
 
diff --git a/tests/test_ssh2.c b/tests/test_ssh2.c
index a1374b8a..2f918cc7 100644
--- a/tests/test_ssh2.c
+++ b/tests/test_ssh2.c
@@ -17,7 +17,7 @@
 #endif
 
 #include <stdio.h>
-#include <stdlib.h>
+#include <stdlib.h>  /* for getenv() */
 
 static const char *hostname = "127.0.0.1";
 static const unsigned short port_number = 4711;