diff --git a/regress/modpipe.c b/regress/modpipe.c
index c43e9cba1..5f4824b51 100755
--- a/regress/modpipe.c
+++ b/regress/modpipe.c
@@ -25,6 +25,9 @@
 #include <stdarg.h>
 #include <stdlib.h>
 #include <errno.h>
+#ifdef HAVE_ERR_H
+# include <err.h>
+#endif
 #include "openbsd-compat/getopt_long.c"
 
 static void