diff --git a/shared/systemd/src/basic/sort-util.h b/shared/systemd/src/basic/sort-util.h
index e029f86..935f136 100644
--- a/shared/systemd/src/basic/sort-util.h
+++ b/shared/systemd/src/basic/sort-util.h
@@ -5,6 +5,13 @@
 
 #include "macro.h"
 
+#ifndef __COMPAR_FN_T
+# define __COMPAR_FN_T
+typedef int (*__compar_fn_t) (const void *, const void *);
+typedef __compar_fn_t comparison_fn_t;
+typedef int (*__compar_d_fn_t) (const void *, const void *, void *);
+#endif
+
 void *xbsearch_r(const void *key, const void *base, size_t nmemb, size_t size,
                  __compar_d_fn_t compar, void *arg);