diff --git a/cpukit/ChangeLog b/cpukit/ChangeLog
index 8d38deb652..0d193e388e 100644
--- a/cpukit/ChangeLog
+++ b/cpukit/ChangeLog
@@ -1,5 +1,6 @@
 2011-12-06	Ralf Corsépius <ralf.corsepius@rtems.org>
 
+	* libcsupport/src/envlock.c: Build conditionally.
 	* configure.ac: Check for envlock.h.
 	Check for decls of __env_lock, __env_unlock.
 
diff --git a/cpukit/libcsupport/src/envlock.c b/cpukit/libcsupport/src/envlock.c
index 667f6052d4..3fe626d154 100644
--- a/cpukit/libcsupport/src/envlock.c
+++ b/cpukit/libcsupport/src/envlock.c
@@ -10,6 +10,11 @@
 #include "config.h"
 #endif
 
+#if defined(HAVE_ENVLOCK_H) \
+  && defined(HAVE_DECL___ENV_LOCK) && defined(HAVE_DECL___ENV_UNLOCK)
+
+#include <envlock.h>
+
 #include <rtems.h>
 #include <sys/reent.h>
 
@@ -105,4 +110,6 @@ __env_unlock(struct _reent *r __attribute__((unused)))
 {
   rtems_libio_unlock();
 }
-#endif
+#endif /* ENVLOCK_DEDICATED_MUTEX */
+
+#endif /* HAVE_ENVLOCK_H ... */