diff --git a/libc/stdio/local.h b/libc/stdio/local.h
index 0ff0785..517935b 100644
--- a/libc/stdio/local.h
+++ b/libc/stdio/local.h
@@ -159,24 +159,12 @@
 #define _UB(fp) _EXT(fp)->_ub
 #define _FLOCK(fp)  _EXT(fp)->_lock
 
-#define _FILEEXT_INIT(fp) \
-do { \
-	_UB(fp)._base = NULL; \
-	_UB(fp)._size = 0; \
-	WCIO_INIT(fp); \
-	pthread_mutexattr_t attr; \
-	pthread_mutexattr_init(&attr); \
-	pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE); \
-	pthread_mutex_init(&_FLOCK(fp), &attr); \
-	pthread_mutexattr_destroy(&attr); \
-	_EXT(fp)->_caller_handles_locking = false; \
-} while (0)
-
-#define _FILEEXT_SETUP(f, fext) \
-do { \
-	(f)->_ext._base = __BIONIC_CAST(reinterpret_cast, unsigned char*, fext); \
-	_FILEEXT_INIT(f); \
-} while (0)
+#define _FILEEXT_SETUP(fp, fext) \
+  do { \
+    (fp)->_ext._base = __BIONIC_CAST(reinterpret_cast, unsigned char*, fext); \
+    memset(_EXT(fp), 0, sizeof(struct __sfileext)); \
+    _EXT(fp)->_caller_handles_locking = true; \
+  } while (0)
 
 /*
  * Android <= KitKat had getc/putc macros in <stdio.h> that referred
diff --git a/libc/stdio/stdio.cpp b/libc/stdio/stdio.cpp
index d627556..d3ac043 100644
--- a/libc/stdio/stdio.cpp
+++ b/libc/stdio/stdio.cpp
@@ -170,7 +170,10 @@
 
 	fp->_lb._base = nullptr;	/* no line buffer */
 	fp->_lb._size = 0;
-	_FILEEXT_INIT(fp);
+
+	memset(_EXT(fp), 0, sizeof(struct __sfileext));
+	_FLOCK(fp) = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
+	_EXT(fp)->_caller_handles_locking = false;
 
 	// Caller sets cookie, _read/_write etc.
 	// We explicitly clear _seek and _seek64 to prevent subtle bugs.
diff --git a/libc/stdio/wcio.h b/libc/stdio/wcio.h
index 2c1fa3c..3c4f7a4 100644
--- a/libc/stdio/wcio.h
+++ b/libc/stdio/wcio.h
@@ -79,9 +79,6 @@
 	} \
 } while (0)
 
-#define WCIO_INIT(fp) \
-	memset(&(_EXT(fp)->_wcio), 0, sizeof(struct wchar_io_data))
-
 __END_DECLS
 
 #endif /*_WCIO_H_*/