diff --git a/libc/bionic/system_properties.c b/libc/bionic/system_properties.c
index 0587430..d969507 100644
--- a/libc/bionic/system_properties.c
+++ b/libc/bionic/system_properties.c
@@ -26,6 +26,7 @@
  * SUCH DAMAGE.
  */
 #include <stdio.h>
+#include <stdint.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <stddef.h>
@@ -49,6 +50,25 @@
 
 #include <sys/atomics.h>
 
+struct prop_area {
+    unsigned volatile count;
+    unsigned volatile serial;
+    unsigned magic;
+    unsigned version;
+    unsigned reserved[4];
+    unsigned toc[1];
+};
+
+typedef struct prop_area prop_area;
+
+struct prop_info {
+    char name[PROP_NAME_MAX];
+    unsigned volatile serial;
+    char value[PROP_VALUE_MAX];
+};
+
+typedef struct prop_info prop_info;
+
 static const char property_service_socket[] = "/dev/socket/" PROP_SERVICE_NAME;
 
 static unsigned dummy_props = 0;
@@ -66,6 +86,17 @@
     return atoi(env);
 }
 
+void __system_property_area_init(void *data)
+{
+    prop_area *pa = data;
+    memset(pa, 0, PA_SIZE);
+    pa->magic = PROP_AREA_MAGIC;
+    pa->version = PROP_AREA_VERSION;
+
+    /* plug into the lib property services */
+    __system_property_area__ = pa;
+}
+
 int __system_properties_init(void)
 {
     bool fromFile = true;
@@ -147,6 +178,11 @@
     unsigned len = strlen(name);
     prop_info *pi;
 
+    if (len >= PROP_NAME_MAX)
+        return 0;
+    if (len < 1)
+        return 0;
+
     while(count--) {
         unsigned entry = *toc++;
         if(TOC_NAME_LEN(entry) != len) continue;
@@ -294,3 +330,68 @@
     }
     return 0;
 }
+
+int __system_property_update(prop_info *pi, const char *value, unsigned int len)
+{
+    prop_area *pa = __system_property_area__;
+
+    if (len >= PROP_VALUE_MAX)
+        return -1;
+
+    pi->serial = pi->serial | 1;
+    memcpy(pi->value, value, len + 1);
+    pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff);
+    __futex_wake(&pi->serial, INT32_MAX);
+
+    pa->serial++;
+    __futex_wake(&pa->serial, INT32_MAX);
+
+    return 0;
+}
+
+int __system_property_add(const char *name, unsigned int namelen,
+            const char *value, unsigned int valuelen)
+{
+    prop_area *pa = __system_property_area__;
+    prop_info *pa_info_array = (void*) (((char*) pa) + PA_INFO_START);
+    prop_info *pi;
+
+    if (pa->count == PA_COUNT_MAX)
+        return -1;
+    if (namelen >= PROP_NAME_MAX)
+        return -1;
+    if (valuelen >= PROP_VALUE_MAX)
+        return -1;
+    if (namelen < 1)
+        return -1;
+
+    pi = pa_info_array + pa->count;
+    pi->serial = (valuelen << 24);
+    memcpy(pi->name, name, namelen + 1);
+    memcpy(pi->value, value, valuelen + 1);
+
+    pa->toc[pa->count] =
+        (namelen << 24) | (((unsigned) pi) - ((unsigned) pa));
+
+    pa->count++;
+    pa->serial++;
+    __futex_wake(&pa->serial, INT32_MAX);
+
+    return 0;
+}
+
+unsigned int __system_property_serial(const prop_info *pi)
+{
+    return pi->serial;
+}
+
+unsigned int __system_property_wait_any(unsigned int serial)
+{
+    prop_area *pa = __system_property_area__;
+
+    do {
+        __futex_wait(&pa->serial, serial, 0);
+    } while(pa->serial == serial);
+
+    return pa->serial;
+}
diff --git a/libc/include/sys/_system_properties.h b/libc/include/sys/_system_properties.h
index 5d2043d..c5bc223 100644
--- a/libc/include/sys/_system_properties.h
+++ b/libc/include/sys/_system_properties.h
@@ -34,7 +34,6 @@
 #else
 #include <sys/system_properties.h>
 
-typedef struct prop_area prop_area;
 typedef struct prop_msg prop_msg;
 
 #define PROP_AREA_MAGIC   0x504f5250
@@ -43,29 +42,20 @@
 #define PROP_SERVICE_NAME "property_service"
 #define PROP_FILENAME "/dev/__properties__"
 
-/* #define PROP_MAX_ENTRIES 247 */
-/* 247 -> 32620 bytes (<32768) */
+/* (8 header words + 247 toc words) = 1020 bytes */
+/* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */
+
+#define PA_COUNT_MAX  247
+#define PA_INFO_START 1024
+#define PA_SIZE       32768
 
 #define TOC_NAME_LEN(toc)       ((toc) >> 24)
 #define TOC_TO_INFO(area, toc)  ((prop_info*) (((char*) area) + ((toc) & 0xFFFFFF)))
 
-struct prop_area {
-    unsigned volatile count;
-    unsigned volatile serial;
-    unsigned magic;
-    unsigned version;
-    unsigned reserved[4];
-    unsigned toc[1];
-};
-
 #define SERIAL_VALUE_LEN(serial) ((serial) >> 24)
 #define SERIAL_DIRTY(serial) ((serial) & 1)
 
-struct prop_info {
-    char name[PROP_NAME_MAX];
-    unsigned volatile serial;
-    char value[PROP_VALUE_MAX];
-};
+__BEGIN_DECLS
 
 struct prop_msg 
 {
@@ -106,5 +96,47 @@
 #define PROP_PATH_LOCAL_OVERRIDE   "/data/local.prop"
 #define PROP_PATH_FACTORY          "/factory/factory.prop"
 
+/*
+** Initialize the area to be used to store properties.  Can
+** only be done by a single process that has write access to
+** the property area.
+*/
+void __system_property_area_init(void *data);
+
+/* Add a new system property.  Can only be done by a single
+** process that has write access to the property area, and
+** that process must handle sequencing to ensure the property
+** does not already exist and that only one property is added
+** or updated at a time.
+**
+** Returns 0 on success, -1 if the property area is full.
+*/
+int __system_property_add(const char *name, unsigned int namelen,
+			const char *value, unsigned int valuelen);
+
+/* Update the value of a system property returned by
+** __system_property_find.  Can only be done by a single process
+** that has write access to the property area, and that process
+** 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 *pi, const char *value, unsigned int len);
+
+/* Read the serial number of a system property returned by
+** __system_property_find.
+**
+** Returns the serial number on success, -1 on error.
+*/
+unsigned int __system_property_serial(const prop_info *pi);
+
+/* Wait for any system property to be updated.  Caller must pass
+** in 0 the first time, and the previous return value on each
+** successive call. */
+unsigned int __system_property_wait_any(unsigned int serial);
+
+__END_DECLS
+
 #endif
 #endif
diff --git a/libc/netbsd/resolv/res_state.c b/libc/netbsd/resolv/res_state.c
index 3e1f67b..2b34867 100644
--- a/libc/netbsd/resolv/res_state.c
+++ b/libc/netbsd/resolv/res_state.c
@@ -71,7 +71,7 @@
         rt->_serial = 0;
         rt->_pi = (struct prop_info*) __system_property_find("net.change");
         if (rt->_pi) {
-            rt->_serial = rt->_pi->serial;
+            rt->_serial = __system_property_serial(rt->_pi);
         }
         memset(rt->_rstatic, 0, sizeof rt->_rstatic);
     }
@@ -135,14 +135,14 @@
                 return rt;
             }
         }
-        if (rt->_serial == rt->_pi->serial) {
+        if (rt->_serial == __system_property_serial(rt->_pi)) {
             /* Nothing changed, so return the current state */
             D("%s: tid=%d rt=%p nothing changed, returning",
               __FUNCTION__, gettid(), rt);
             return rt;
         }
         /* Update the recorded serial number, and go reset the state */
-        rt->_serial = rt->_pi->serial;
+        rt->_serial = __system_property_serial(rt->_pi);
         goto RESET_STATE;
     }