diff --git a/include/libssh2_sftp.h b/include/libssh2_sftp.h
index 476ea870..d35ff27a 100644
--- a/include/libssh2_sftp.h
+++ b/include/libssh2_sftp.h
@@ -231,10 +231,11 @@ libssh2_sftp_open_ex(LIBSSH2_SFTP *sftp,
                      unsigned long flags,
                      long mode, int open_type);
 #define libssh2_sftp_open(sftp, filename, flags, mode)                  \
-    libssh2_sftp_open_ex((sftp), (filename), strlen(filename), (flags), \
-                         (mode), LIBSSH2_SFTP_OPENFILE)
+    libssh2_sftp_open_ex((sftp), \
+                         (filename), (unsigned int)strlen(filename), \
+                         (flags), (mode), LIBSSH2_SFTP_OPENFILE)
 #define libssh2_sftp_opendir(sftp, path) \
-    libssh2_sftp_open_ex((sftp), (path), strlen(path), 0, 0, \
+    libssh2_sftp_open_ex((sftp), (path), (unsigned int)strlen(path), 0, 0, \
                          LIBSSH2_SFTP_OPENDIR)
 
 LIBSSH2_API ssize_t libssh2_sftp_read(LIBSSH2_SFTP_HANDLE *handle,
@@ -281,8 +282,9 @@ LIBSSH2_API int libssh2_sftp_rename_ex(LIBSSH2_SFTP *sftp,
                                        unsigned int dest_filename_len,
                                        long flags);
 #define libssh2_sftp_rename(sftp, sourcefile, destfile) \
-    libssh2_sftp_rename_ex((sftp), (sourcefile), strlen(sourcefile), \
-                           (destfile), strlen(destfile),                \
+    libssh2_sftp_rename_ex((sftp), \
+                           (sourcefile), (unsigned int)strlen(sourcefile), \
+                           (destfile), (unsigned int)strlen(destfile), \
                            LIBSSH2_SFTP_RENAME_OVERWRITE | \
                            LIBSSH2_SFTP_RENAME_ATOMIC | \
                            LIBSSH2_SFTP_RENAME_NATIVE)
@@ -305,13 +307,13 @@ LIBSSH2_API int libssh2_sftp_mkdir_ex(LIBSSH2_SFTP *sftp,
                                       const char *path,
                                       unsigned int path_len, long mode);
 #define libssh2_sftp_mkdir(sftp, path, mode) \
-    libssh2_sftp_mkdir_ex((sftp), (path), strlen(path), (mode))
+    libssh2_sftp_mkdir_ex((sftp), (path), (unsigned int)strlen(path), (mode))
 
 LIBSSH2_API int libssh2_sftp_rmdir_ex(LIBSSH2_SFTP *sftp,
                                       const char *path,
                                       unsigned int path_len);
 #define libssh2_sftp_rmdir(sftp, path) \
-    libssh2_sftp_rmdir_ex((sftp), (path), strlen(path))
+    libssh2_sftp_rmdir_ex((sftp), (path), (unsigned int)strlen(path))
 
 LIBSSH2_API int libssh2_sftp_stat_ex(LIBSSH2_SFTP *sftp,
                                      const char *path,
@@ -319,14 +321,14 @@ LIBSSH2_API int libssh2_sftp_stat_ex(LIBSSH2_SFTP *sftp,
                                      int stat_type,
                                      LIBSSH2_SFTP_ATTRIBUTES *attrs);
 #define libssh2_sftp_stat(sftp, path, attrs) \
-    libssh2_sftp_stat_ex((sftp), (path), strlen(path), LIBSSH2_SFTP_STAT, \
-                         (attrs))
+    libssh2_sftp_stat_ex((sftp), (path), (unsigned int)strlen(path), \
+                         LIBSSH2_SFTP_STAT, (attrs))
 #define libssh2_sftp_lstat(sftp, path, attrs) \
-    libssh2_sftp_stat_ex((sftp), (path), strlen(path), LIBSSH2_SFTP_LSTAT, \
-                         (attrs))
+    libssh2_sftp_stat_ex((sftp), (path), (unsigned int)strlen(path), \
+                         LIBSSH2_SFTP_LSTAT, (attrs))
 #define libssh2_sftp_setstat(sftp, path, attrs) \
-    libssh2_sftp_stat_ex((sftp), (path), strlen(path), LIBSSH2_SFTP_SETSTAT, \
-                         (attrs))
+    libssh2_sftp_stat_ex((sftp), (path), (unsigned int)strlen(path), \
+                         LIBSSH2_SFTP_SETSTAT, (attrs))
 
 LIBSSH2_API int libssh2_sftp_symlink_ex(LIBSSH2_SFTP *sftp,
                                         const char *path,
@@ -335,13 +337,19 @@ LIBSSH2_API int libssh2_sftp_symlink_ex(LIBSSH2_SFTP *sftp,
                                         unsigned int target_len,
                                         int link_type);
 #define libssh2_sftp_symlink(sftp, orig, linkpath) \
-    libssh2_sftp_symlink_ex((sftp), (orig), strlen(orig), (linkpath), \
-                            strlen(linkpath), LIBSSH2_SFTP_SYMLINK)
+    libssh2_sftp_symlink_ex((sftp), \
+                            (orig), (unsigned int)strlen(orig), \
+                            (linkpath), (unsigned int)strlen(linkpath), \
+                            LIBSSH2_SFTP_SYMLINK)
 #define libssh2_sftp_readlink(sftp, path, target, maxlen) \
-    libssh2_sftp_symlink_ex((sftp), (path), strlen(path), (target), (maxlen), \
-    LIBSSH2_SFTP_READLINK)
+    libssh2_sftp_symlink_ex((sftp), \
+                            (path), (unsigned int)strlen(path), \
+                            (target), (maxlen), \
+                            LIBSSH2_SFTP_READLINK)
 #define libssh2_sftp_realpath(sftp, path, target, maxlen) \
-    libssh2_sftp_symlink_ex((sftp), (path), strlen(path), (target), (maxlen), \
+    libssh2_sftp_symlink_ex((sftp), \
+                            (path), (unsigned int)strlen(path), \
+                            (target), (maxlen), \
                             LIBSSH2_SFTP_REALPATH)
 
 #ifdef __cplusplus