diff --git a/Misc/ACKS b/Misc/ACKS
index e8aac41..f3e427a 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -327,6 +327,7 @@
 Walter Dörwald
 Hans Eckardt
 Rodolpho Eckhardt
+David Edelsohn
 John Edmonds
 Grant Edwards
 John Ehresman
diff --git a/Misc/NEWS b/Misc/NEWS
index a9eeeff..d9b3f4e 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -141,6 +141,9 @@
 Build
 -----
 
+- Issue #18256: Compilation fix for recent AIX releases.  Patch by
+  David Edelsohn.
+
 - Issue #15172: Document NASM 2.10+ as requirement for building OpenSSL 1.0.1
   on Windows.
 
diff --git a/Python/thread_pthread.h b/Python/thread_pthread.h
index 49713ce..e90ae7e 100644
--- a/Python/thread_pthread.h
+++ b/Python/thread_pthread.h
@@ -170,6 +170,7 @@
 PyThread__init_thread(void)
 {
 #if defined(_AIX) && defined(__GNUC__)
+    extern void pthread_init(void);
     pthread_init();
 #endif
 }
@@ -444,6 +445,7 @@
     pthread_lock *thelock = (pthread_lock *)lock;
     int status, error = 0;
 
+    (void) error; /* silence unused-but-set-variable warning */
     dprintf(("PyThread_free_lock(%p) called\n", lock));
 
     /* some pthread-like implementations tie the mutex to the cond
@@ -530,6 +532,7 @@
     pthread_lock *thelock = (pthread_lock *)lock;
     int status, error = 0;
 
+    (void) error; /* silence unused-but-set-variable warning */
     dprintf(("PyThread_release_lock(%p) called\n", lock));
 
     status = pthread_mutex_lock( &thelock->mut );