diff --git a/namespaces/nsenter/nsenter.c b/namespaces/nsenter/nsenter.c
index 1f6947893..1a81c3157 100644
--- a/namespaces/nsenter/nsenter.c
+++ b/namespaces/nsenter/nsenter.c
@@ -15,6 +15,10 @@
 #include <unistd.h>
 #include <getopt.h>
 
+#ifndef PR_SET_CHILD_SUBREAPER
+#define PR_SET_CHILD_SUBREAPER 36
+#endif
+
 static const kBufSize = 256;
 static const char *kNsEnter = "nsenter";