diff --git a/Misc/NEWS b/Misc/NEWS
index d7f6d1f..d8f2f1b 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,9 @@
 Core and Builtins
 -----------------
 
+- Issue #9862: Compensate for broken PIPE_BUF in AIX by hard coding
+  its value as the default 512 when compiling on AIX.
+
 - Issue #10068: Global objects which have reference cycles with their module's
   dict are now cleared again. This causes issue #7140 to appear again.
 
diff --git a/Modules/selectmodule.c b/Modules/selectmodule.c
index 1b88c98..086a647 100644
--- a/Modules/selectmodule.c
+++ b/Modules/selectmodule.c
@@ -1768,6 +1768,10 @@
     PyModule_AddObject(m, "error", SelectError);
 
 #ifdef PIPE_BUF
+#ifdef HAVE_BROKEN_PIPE_BUF
+#undef PIPE_BUF
+#define PIPE_BUF 512
+#endif
     PyModule_AddIntConstant(m, "PIPE_BUF", PIPE_BUF);
 #endif
 
diff --git a/configure.in b/configure.in
index bfa5ba5..3a87ff1 100644
--- a/configure.in
+++ b/configure.in
@@ -4261,6 +4261,12 @@
 #endif
 ])
 
+case $ac_sys_system in
+AIX*)
+  AC_DEFINE(HAVE_BROKEN_PIPE_BUF, 1, [Define if the system reports an invalid PIPE_BUF value.]) ;;
+esac
+
+
 AC_SUBST(THREADHEADERS)
 
 for h in `(cd $srcdir;echo Python/thread_*.h)`