diff --git a/libcilkrts/configure b/libcilkrts/configure
index 91da0a8..63181d7 100644
--- a/libcilkrts/configure
+++ b/libcilkrts/configure
@@ -14420,6 +14420,38 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
 
+# Check for pthread_{,attr_}[sg]etaffinity_np.
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#define _GNU_SOURCE
+   #include <pthread.h>
+int
+main ()
+{
+cpu_set_t cpuset;
+   pthread_attr_t attr;
+   pthread_getaffinity_np (pthread_self (), sizeof (cpu_set_t), &cpuset);
+   if (CPU_ISSET (0, &cpuset))
+     CPU_SET (1, &cpuset);
+   else
+     CPU_ZERO (&cpuset);
+   pthread_setaffinity_np (pthread_self (), sizeof (cpu_set_t), &cpuset);
+   pthread_attr_init (&attr);
+   pthread_attr_getaffinity_np (&attr, sizeof (cpu_set_t), &cpuset);
+   pthread_attr_setaffinity_np (&attr, sizeof (cpu_set_t), &cpuset);
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+
+$as_echo "#define HAVE_PTHREAD_AFFINITY_NP 1" >>confdefs.h
+
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+
+
 # Must be last
 cat >confcache <<\_ACEOF
 # This file is a shell script that caches the results of configure
diff --git a/libcilkrts/configure.ac b/libcilkrts/configure.ac
index 30fac99..61b45b0 100644
--- a/libcilkrts/configure.ac
+++ b/libcilkrts/configure.ac
@@ -164,5 +164,25 @@ AC_SUBST(toolexeclibdir)
 
 AC_SUBST(lt_cv_dlopen_libs)
 
+# Check for pthread_{,attr_}[sg]etaffinity_np.
+AC_LINK_IFELSE(
+ [AC_LANG_PROGRAM(
+  [#define _GNU_SOURCE
+   #include <pthread.h>],
+  [cpu_set_t cpuset;
+   pthread_attr_t attr;
+   pthread_getaffinity_np (pthread_self (), sizeof (cpu_set_t), &cpuset);
+   if (CPU_ISSET (0, &cpuset))
+     CPU_SET (1, &cpuset);
+   else
+     CPU_ZERO (&cpuset);
+   pthread_setaffinity_np (pthread_self (), sizeof (cpu_set_t), &cpuset);
+   pthread_attr_init (&attr);
+   pthread_attr_getaffinity_np (&attr, sizeof (cpu_set_t), &cpuset);
+   pthread_attr_setaffinity_np (&attr, sizeof (cpu_set_t), &cpuset);])],
+  AC_DEFINE(HAVE_PTHREAD_AFFINITY_NP, 1,
+[       Define if pthread_{,attr_}{g,s}etaffinity_np is supported.]))
+
+
 # Must be last
 AC_OUTPUT
diff --git a/libcilkrts/runtime/os-unix.c b/libcilkrts/runtime/os-unix.c
index dbca21f..fafb91d 100644
--- a/libcilkrts/runtime/os-unix.c
+++ b/libcilkrts/runtime/os-unix.c
@@ -311,6 +311,10 @@ static pid_t linux_gettid(void)
  */
 static int linux_get_affinity_count (int tid) 
 {
+#if !defined HAVE_PTHREAD_AFFINITY_NP
+  return 0;
+#else
+
     cpu_set_t process_mask;
 
     // Extract the thread affinity mask
@@ -337,6 +341,7 @@ static int linux_get_affinity_count (int tid)
     }
 
     return available_procs;
+#endif
 }
 #endif