diff --git a/libc/bionic/system_property_api.cpp b/libc/bionic/system_property_api.cpp
index 8fdea59..ed30fc2 100644
--- a/libc/bionic/system_property_api.cpp
+++ b/libc/bionic/system_property_api.cpp
@@ -26,8 +26,7 @@
  * SUCH DAMAGE.
  */
 
-#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
-#include <sys/_system_properties.h>
+#include <sys/system_properties.h>
 
 #include <async_safe/CHECK.h>
 #include <system_properties/prop_area.h>
diff --git a/libc/bionic/system_property_set.cpp b/libc/bionic/system_property_set.cpp
index 73cf151..9d73445 100644
--- a/libc/bionic/system_property_set.cpp
+++ b/libc/bionic/system_property_set.cpp
@@ -34,11 +34,10 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/socket.h>
+#include <sys/system_properties.h>
 #include <sys/types.h>
 #include <sys/uio.h>
 #include <sys/un.h>
-#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
-#include <sys/_system_properties.h>
 #include <unistd.h>
 
 #include <async_safe/log.h>
diff --git a/libc/include/sys/_system_properties.h b/libc/include/sys/_system_properties.h
index 05612b3..12cafec 100644
--- a/libc/include/sys/_system_properties.h
+++ b/libc/include/sys/_system_properties.h
@@ -1,172 +1 @@
-/*
- * Copyright (C) 2008 The Android Open Source Project
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *  * Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- *  * Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#pragma once
-
-#include <sys/cdefs.h>
-#include <stdint.h>
-
-#ifndef _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
-#error you should #include <sys/system_properties.h> instead
-#endif
-
 #include <sys/system_properties.h>
-
-__BEGIN_DECLS
-
-/**
- * Reads the global serial number of the system properties _area_.
- *
- * Called to predict if a series of cached __system_property_find()
- * objects will have seen __system_property_serial() values change.
- * Also aids the converse, as changes in the global serial can
- * also be used to predict if a failed __system_property_find()
- * could in turn now find a new object; thus preventing the
- * cycles of effort to poll __system_property_find().
- *
- * Typically called at beginning of a cache cycle to signal if _any_ possible
- * changes have occurred since last. If there is, one may check each individual
- * __system_property_serial() to confirm dirty, or __system_property_find()
- * to check if the property now exists. If a call to __system_property_add()
- * or __system_property_update() has completed between two calls to
- * __system_property_area_serial() then the second call will return a larger
- * value than the first call. Beware of race conditions as changes to the
- * properties are not atomic, the main value of this call is to determine
- * whether the expensive __system_property_find() is worth retrying to see if
- * a property now exists.
- *
- * Returns the serial number on success, -1 on error.
- */
-uint32_t __system_property_area_serial(void);
-
-/**
- * Reads the serial number of a specific system property previously returned by
- * __system_property_find(). This is a cheap way to check whether a system
- * property has changed or not.
- *
- * Returns the serial number on success, -1 on error.
- */
-uint32_t __system_property_serial(const prop_info* _Nonnull __pi);
-
-//
-// libc implementation detail.
-//
-
-/**
- * Initializes the system properties area in read-only mode.
- *
- * This is called automatically during libc initialization,
- * so user code should never need to call this.
- *
- * Returns 0 on success, -1 otherwise.
- */
-int __system_properties_init(void);
-
-//
-// init implementation details.
-//
-
-#define PROP_SERVICE_NAME "property_service"
-#define PROP_SERVICE_FOR_SYSTEM_NAME "property_service_for_system"
-#define PROP_DIRNAME "/dev/__properties__"
-
-// Messages sent to init.
-#define PROP_MSG_SETPROP 1
-#define PROP_MSG_SETPROP2 0x00020001
-
-// Status codes returned by init (but not passed from libc to the caller).
-#define PROP_SUCCESS 0
-#define PROP_ERROR_READ_CMD 0x0004
-#define PROP_ERROR_READ_DATA 0x0008
-#define PROP_ERROR_READ_ONLY_PROPERTY 0x000B
-#define PROP_ERROR_INVALID_NAME 0x0010
-#define PROP_ERROR_INVALID_VALUE 0x0014
-#define PROP_ERROR_PERMISSION_DENIED 0x0018
-#define PROP_ERROR_INVALID_CMD 0x001B
-#define PROP_ERROR_HANDLE_CONTROL_MESSAGE 0x0020
-#define PROP_ERROR_SET_FAILED 0x0024
-
-/**
- * Initializes the area to be used to store properties.
- *
- * Can only be done by the process that has write access to the property area,
- * typically init.
- *
- * See __system_properties_init() for the equivalent for all other processes.
- */
-int __system_property_area_init(void);
-
-/**
- * Adds a new system property.
- * Can only be done by the process that has write access to the property area --
- * typically init -- which must handle sequencing to ensure that only one property is
- * updated at a time.
- *
- * Returns 0 on success, -1 if the property area is full.
- */
-int __system_property_add(const char* _Nonnull __name, unsigned int __name_length, const char* _Nonnull __value, unsigned int __value_length);
-
-/**
- * Updates the value of a system property returned by __system_property_find().
- * Can only be done by the process that has write access to the property area --
- * typically init -- which must handle sequencing to ensure that only one property is
- * updated at a time.
- *
- * Returns 0 on success, -1 if the parameters are incorrect.
- */
-int __system_property_update(prop_info* _Nonnull __pi, const char* _Nonnull __value, unsigned int __value_length);
-
-/**
- * Reloads the system properties from disk.
- * Not intended for use by any apps except the Zygote.
- * Should only be called from the main thread.
- *
- * Pointers received from functions such as __system_property_find()
- * may be invalidated by calls to this function.
- *
- * Returns 0 on success, -1 otherwise.
- *
- * Available since API level 35.
- */
-int __system_properties_zygote_reload(void) __INTRODUCED_IN(35);
-
-//
-// Deprecated functions.
-//
-
-/** Deprecated: use __system_property_wait instead. */
-uint32_t __system_property_wait_any(uint32_t __old_serial);
-
-/**
- * Deprecated: previously for testing, but now that SystemProperties is its own
- * testable class, there is never a reason to call this function and its
- * implementation simply returns -1.
- */
-int __system_property_set_filename(const char* __unused __filename);
-
-__END_DECLS
diff --git a/libc/include/sys/system_properties.h b/libc/include/sys/system_properties.h
index ae94db5..e8b6e34 100644
--- a/libc/include/sys/system_properties.h
+++ b/libc/include/sys/system_properties.h
@@ -110,11 +110,136 @@
  */
 #define PROP_NAME_MAX   32
 
+/** Deprecated. Use __system_property_foreach() instead. */
+const prop_info* _Nullable __system_property_find_nth(unsigned __n);
 /** Deprecated. Use __system_property_read_callback() instead. */
 int __system_property_read(const prop_info* _Nonnull __pi, char* _Nullable __name, char* _Nonnull __value);
 /** Deprecated. Use __system_property_read_callback() instead. */
 int __system_property_get(const char* _Nonnull __name, char* _Nonnull __value);
-/** Deprecated. Use __system_property_foreach() instead. */
-const prop_info* _Nullable __system_property_find_nth(unsigned __n);
+/** Deprecated: use __system_property_wait() instead. */
+uint32_t __system_property_wait_any(uint32_t __old_serial);
+
+/**
+ * Reads the global serial number of the system properties _area_.
+ *
+ * Called to predict if a series of cached __system_property_find()
+ * objects will have seen __system_property_serial() values change.
+ * Also aids the converse, as changes in the global serial can
+ * also be used to predict if a failed __system_property_find()
+ * could in turn now find a new object; thus preventing the
+ * cycles of effort to poll __system_property_find().
+ *
+ * Typically called at beginning of a cache cycle to signal if _any_ possible
+ * changes have occurred since last. If there is, one may check each individual
+ * __system_property_serial() to confirm dirty, or __system_property_find()
+ * to check if the property now exists. If a call to __system_property_add()
+ * or __system_property_update() has completed between two calls to
+ * __system_property_area_serial() then the second call will return a larger
+ * value than the first call. Beware of race conditions as changes to the
+ * properties are not atomic, the main value of this call is to determine
+ * whether the expensive __system_property_find() is worth retrying to see if
+ * a property now exists.
+ *
+ * Returns the serial number on success, -1 on error.
+ */
+uint32_t __system_property_area_serial(void);
+
+/**
+ * Reads the serial number of a specific system property previously returned by
+ * __system_property_find(). This is a cheap way to check whether a system
+ * property has changed or not.
+ *
+ * Returns the serial number on success, -1 on error.
+ */
+uint32_t __system_property_serial(const prop_info* _Nonnull __pi);
+
+//
+// libc implementation detail.
+//
+
+/**
+ * Initializes the system properties area in read-only mode.
+ *
+ * This is called automatically during libc initialization,
+ * so user code should never need to call this.
+ *
+ * Returns 0 on success, -1 otherwise.
+ */
+int __system_properties_init(void);
+
+//
+// init implementation details.
+//
+
+#define PROP_SERVICE_NAME "property_service"
+#define PROP_SERVICE_FOR_SYSTEM_NAME "property_service_for_system"
+#define PROP_DIRNAME "/dev/__properties__"
+
+// Messages sent to init.
+#define PROP_MSG_SETPROP 1
+#define PROP_MSG_SETPROP2 0x00020001
+
+// Status codes returned by init (but not passed from libc to the caller).
+#define PROP_SUCCESS 0
+#define PROP_ERROR_READ_CMD 0x0004
+#define PROP_ERROR_READ_DATA 0x0008
+#define PROP_ERROR_READ_ONLY_PROPERTY 0x000B
+#define PROP_ERROR_INVALID_NAME 0x0010
+#define PROP_ERROR_INVALID_VALUE 0x0014
+#define PROP_ERROR_PERMISSION_DENIED 0x0018
+#define PROP_ERROR_INVALID_CMD 0x001B
+#define PROP_ERROR_HANDLE_CONTROL_MESSAGE 0x0020
+#define PROP_ERROR_SET_FAILED 0x0024
+
+/**
+ * Initializes the area to be used to store properties.
+ *
+ * Can only be done by the process that has write access to the property area,
+ * typically init.
+ *
+ * See __system_properties_init() for the equivalent for all other processes.
+ */
+int __system_property_area_init(void);
+
+/**
+ * Adds a new system property.
+ * Can only be done by the process that has write access to the property area --
+ * typically init -- which must handle sequencing to ensure that only one property is
+ * updated at a time.
+ *
+ * Returns 0 on success, -1 if the property area is full.
+ */
+int __system_property_add(const char* _Nonnull __name, unsigned int __name_length, const char* _Nonnull __value, unsigned int __value_length);
+
+/**
+ * Updates the value of a system property returned by __system_property_find().
+ * Can only be done by the process that has write access to the property area --
+ * typically init -- which must handle sequencing to ensure that only one property is
+ * updated at a time.
+ *
+ * Returns 0 on success, -1 if the parameters are incorrect.
+ */
+int __system_property_update(prop_info* _Nonnull __pi, const char* _Nonnull __value, unsigned int __value_length);
+
+/**
+ * Reloads the system properties from disk.
+ * Not intended for use by any apps except the Zygote.
+ * Should only be called from the main thread.
+ *
+ * Pointers received from functions such as __system_property_find()
+ * may be invalidated by calls to this function.
+ *
+ * Returns 0 on success, -1 otherwise.
+ *
+ * Available since API level 35.
+ */
+int __system_properties_zygote_reload(void) __INTRODUCED_IN(35);
+
+/**
+ * Deprecated: previously for testing, but now that SystemProperties is its own
+ * testable class, there is never a reason to call this function and its
+ * implementation simply returns -1.
+ */
+int __system_property_set_filename(const char* _Nullable __unused __filename);
 
 __END_DECLS
diff --git a/libc/private/CachedProperty.h b/libc/private/CachedProperty.h
index bd67d74..7accdb3 100644
--- a/libc/private/CachedProperty.h
+++ b/libc/private/CachedProperty.h
@@ -29,9 +29,7 @@
 #pragma once
 
 #include <string.h>
-
-#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
-#include <sys/_system_properties.h>
+#include <sys/system_properties.h>
 
 // Cached system property lookup. For code that needs to read the same property multiple times,
 // this class helps optimize those lookups.