diff --git a/libc/include/stdio.h b/libc/include/stdio.h
index f9dfa42a..3ad89399 100644
--- a/libc/include/stdio.h
+++ b/libc/include/stdio.h
@@ -16,9 +16,31 @@
  */
 #define EOF (-1)
 
+struct _IO_marker
+{
+    struct _IO_marker *_next;
+    struct _IO_FILE *_sbuf;
+    int _pos;
+};
+
 struct _IO_FILE
 {
-    size_t offset;
+    int _flags;
+
+    char *_IO_read_ptr;
+    char *_IO_read_end;
+    char *_IO_read_base;
+    char *_IO_write_base;
+    char *_IO_write_ptr;
+    char *_IO_write_end;
+    char *_IO_buf_base;
+    char *_IO_buf_end;
+
+    __off_t _offset;
+
+    struct _IO_marker *_markers;
+    struct _IO_FILE *_chain;
+    int _fileno;
 
     void *KernelPrivate;
 };
diff --git a/libc/include/sys/stat.h b/libc/include/sys/stat.h
index 6dbd35c9..61e31c01 100644
--- a/libc/include/sys/stat.h
+++ b/libc/include/sys/stat.h
@@ -1,15 +1,15 @@
 #ifndef _SYS_STAT_H
 #define _SYS_STAT_H
 
-typedef unsigned int _dev_t;
-typedef unsigned short _ino_t;
-typedef unsigned short _mode_t;
-typedef long _off_t;
+typedef unsigned int __dev_t;
+typedef unsigned short __ino_t;
+typedef unsigned short __mode_t;
+typedef long __off_t;
 
-#define dev_t _dev_t
-#define ino_t _ino_t
-#define mode_t _mode_t
-#define off_t _off_t
+#define dev_t __dev_t
+#define ino_t __ino_t
+#define mode_t __mode_t
+#define off_t __off_t
 
 int mkdir(const char *path, mode_t mode);
 int remove(const char *pathname);
diff --git a/libc/src/Runtime.c b/libc/src/Runtime.c
index fd54f1ce..ba855b4e 100644
--- a/libc/src/Runtime.c
+++ b/libc/src/Runtime.c
@@ -2,13 +2,18 @@
 extern void __libc_init_array(void);
 extern void __libc_fini_array(void);
 
+extern void __libc_init_std(void);
+extern void __libc_fini_std(void);
+
 void __libc_init(void)
 {
     __libc_init_array();
+    __libc_init_std();
 }
 
 void _exit(int Code)
 {
+    __libc_fini_std();
     __libc_fini_array();
     __asm__ __volatile__("syscall"
                          :
diff --git a/libc/src/std/io/file.c b/libc/src/std/io/file.c
index 702a5e31..592603db 100644
--- a/libc/src/std/io/file.c
+++ b/libc/src/std/io/file.c
@@ -27,7 +27,7 @@ size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream)
         return 0;
     }
 
-    return syscall4(_FileRead, (uint64_t)stream->KernelPrivate, stream->offset, (uint64_t)ptr, size * nmemb);
+    return syscall4(_FileRead, (uint64_t)stream->KernelPrivate, stream->_offset, (uint64_t)ptr, size * nmemb);
 }
 
 size_t fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream)
@@ -38,7 +38,7 @@ size_t fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream)
         return 0;
     }
 
-    return syscall4(_FileWrite, (uint64_t)stream->KernelPrivate, stream->offset, (uint64_t)ptr, size * nmemb);
+    return syscall4(_FileWrite, (uint64_t)stream->KernelPrivate, stream->_offset, (uint64_t)ptr, size * nmemb);
 }
 
 int fclose(FILE *fp)
@@ -56,7 +56,7 @@ int fclose(FILE *fp)
 
 off_t fseek(FILE *stream, long offset, int whence)
 {
-    if (stream == NULL)
+    if (stream == NULL || whence < 0 || whence > 2)
     {
         errno = EINVAL;
         return -1;
@@ -65,23 +65,40 @@ off_t fseek(FILE *stream, long offset, int whence)
     off_t new_offset = syscall3(_FileSeek, stream->KernelPrivate, offset, whence);
     if (IsSyscallError(new_offset))
         return -1;
-    stream->offset = new_offset;
+    stream->_offset = new_offset;
     return new_offset;
 }
 
 long ftell(FILE *stream)
 {
-    return stream->offset;
+    return stream->_offset;
 }
 
 int fflush(FILE *stream)
 {
-    return 0;
+    if (stream == NULL)
+    {
+        errno = EINVAL;
+        return EOF;
+    }
+
+    errno = ENOSYS;
+    return EOF;
 }
 
 int fprintf(FILE *stream, const char *format, ...)
 {
-    return 0; // sprintf(char *s, const char *format, ...)
+    if (stream == NULL || format == NULL)
+    {
+        errno = EINVAL;
+        return -1;
+    }
+
+    va_list args;
+    va_start(args, format);
+    const int ret = vfprintf(stream, format, args);
+    va_end(args);
+    return ret;
 }
 
 void setbuf(FILE *stream, char *buf)
diff --git a/libc/src/std/io/put.c b/libc/src/std/io/put.c
index c7332ecc..f37c650f 100644
--- a/libc/src/std/io/put.c
+++ b/libc/src/std/io/put.c
@@ -4,13 +4,17 @@
 
 int fputc(int c, FILE *stream)
 {
+    // FIXME
+    // if (stream == NULL)
+    // {
+    //     errno = EBADF;
+    //     return EOF;
+    // }
+
     return syscall2(_Print, c, 0);
 }
 
-int putc(int c, FILE *stream)
-{
-    return syscall2(_Print, c, 0);
-}
+int putc(int c, FILE *stream) { return fputc(c, stream); }
 
 int fputs(const char *s, FILE *stream)
 {
@@ -24,12 +28,5 @@ int puts(const char *s)
         fputc(s[i], stdout);
 }
 
-int putchar(int c)
-{
-    return putc(c, stdout);
-}
-
-void perror(const char *s)
-{
-    fputs(s, stderr);
-}
\ No newline at end of file
+int putchar(int c) { return fputc(c, stdout); }
+void perror(const char *s) { fputs(s, stderr); }
diff --git a/libc/src/std/std_init.c b/libc/src/std/std_init.c
new file mode 100644
index 00000000..aae8d0f5
--- /dev/null
+++ b/libc/src/std/std_init.c
@@ -0,0 +1,13 @@
+#include <stdio.h>
+
+#include "../../../Kernel/syscalls.h"
+
+void __libc_init_std(void)
+{
+    /* FIXME: Temporal workaround */
+    // int IsCritical = syscall1(_KernelCTL, 6 /* KCTL_IS_CRITICAL */);
+}
+
+void __libc_fini_std(void)
+{
+}
diff --git a/libc/src/std/uni/exe.c b/libc/src/std/uni/exe.c
index 7fd31f56..728dae02 100644
--- a/libc/src/std/uni/exe.c
+++ b/libc/src/std/uni/exe.c
@@ -5,36 +5,43 @@
 
 int execl(const char *pathname, const char *arg, ...)
 {
+    errno = ENOSYS;
     return -1;
 }
 
 int execlp(const char *file, const char *arg, ...)
 {
+    errno = ENOSYS;
     return -1;
 }
 
 int execle(const char *pathname, const char *arg, ...)
 {
+    errno = ENOSYS;
     return -1;
 }
 
 int execv(const char *pathname, char *const argv[])
 {
+    errno = ENOSYS;
     return -1;
 }
 
 int execvp(const char *file, char *const argv[])
 {
+    errno = ENOSYS;
     return -1;
 }
 
 int execvpe(const char *file, char *const argv[], char *const envp[])
 {
+    errno = ENOSYS;
     return -1;
 }
 
 int execve(const char *pathname, char *const argv[], char *const envp[])
 {
+    errno = ENOSYS;
     return -1;
 }