diff --git a/libc/bionic/system_properties_compat.c b/libc/bionic/system_properties_compat.c
index 0326f05..b4c2494 100644
--- a/libc/bionic/system_properties_compat.c
+++ b/libc/bionic/system_properties_compat.c
@@ -101,7 +101,7 @@
     for(;;) {
         serial = pi->serial;
         while(SERIAL_DIRTY(serial)) {
-            __futex_wait((volatile void *)&pi->serial, serial, 0);
+            __futex_wait((volatile void *)&pi->serial, serial, NULL);
             serial = pi->serial;
         }
         len = SERIAL_VALUE_LEN(serial);