# define lock_unlock(lock) __libc_lock_unlock (lock)
#elif defined GNULIB_LOCK
# include "glthread/lock.h"
-# define lock_define(name) gl_lock_define (, name)
+ /* Use gl_lock_define if empty macro arguments are known to work.
+ Otherwise, fall back on less-portable substitutes. */
+# if ((defined __GNUC__ && !defined __STRICT_ANSI__) \
+ || (defined __STDC_VERSION__ && 199901L <= __STDC_VERSION__))
+# define lock_define(name) gl_lock_define (, name)
+# elif USE_POSIX_THREADS
+# define lock_define(name) pthread_mutex_t name;
+# elif USE_PTH_THREADS
+# define lock_define(name) pth_mutex_t name;
+# elif USE_SOLARIS_THREADS
+# define lock_define(name) mutex_t name;
+# elif USE_WINDOWS_THREADS
+# define lock_define(name) gl_lock_t name;
+# else
+# define lock_define(name)
+# endif
# define lock_init(lock) glthread_lock_init (&(lock))
# define lock_fini(lock) glthread_lock_destroy (&(lock))
# define lock_lock(lock) glthread_lock_lock (&(lock))