diff --git a/osdep/io.c b/osdep/io.c
index a8210dc89f..6c3c8b7c36 100644
--- a/osdep/io.c
+++ b/osdep/io.c
@@ -708,7 +708,7 @@ char ***mp_penviron(void)
     return &utf8_environ;  // `environ' should be an l-value
 }
 
-off_t mp_lseek(int fd, off_t offset, int whence)
+off_t mp_lseek64(int fd, off_t offset, int whence)
 {
     HANDLE h = (HANDLE)_get_osfhandle(fd);
     if (h != INVALID_HANDLE_VALUE && GetFileType(h) != FILE_TYPE_DISK) {
diff --git a/osdep/io.h b/osdep/io.h
index b8a7c93c1e..722413456d 100644
--- a/osdep/io.h
+++ b/osdep/io.h
@@ -130,7 +130,9 @@ char *mp_getenv(const char *name);
 #define environ (*mp_penviron())  /* ensure initialization and l-value */
 char ***mp_penviron(void);
 
-off_t mp_lseek(int fd, off_t offset, int whence);
+#undef off_t
+#define off_t int64_t
+off_t mp_lseek64(int fd, off_t offset, int whence);
 void *mp_dlopen(const char *filename, int flag);
 void *mp_dlsym(void *handle, const char *symbol);
 char *mp_dlerror(void);
@@ -194,7 +196,7 @@ void mp_globfree(mp_glob_t *pglob);
 #define getenv(...) mp_getenv(__VA_ARGS__)
 
 #undef lseek
-#define lseek(...) mp_lseek(__VA_ARGS__)
+#define lseek(...) mp_lseek64(__VA_ARGS__)
 
 #define RTLD_NOW 0
 #define RTLD_LOCAL 0