diff --git a/findutils/grep.c b/findutils/grep.c
index c43ad0134..05bf8b8cf 100644
--- a/findutils/grep.c
+++ b/findutils/grep.c
@@ -22,7 +22,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
-#include <unistd.h> /* for getopt() */
+#include <getopt.h>
 #include <regex.h>
 #include <string.h> /* for strerror() */
 #include <errno.h>
diff --git a/grep.c b/grep.c
index c43ad0134..05bf8b8cf 100644
--- a/grep.c
+++ b/grep.c
@@ -22,7 +22,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
-#include <unistd.h> /* for getopt() */
+#include <getopt.h>
 #include <regex.h>
 #include <string.h> /* for strerror() */
 #include <errno.h>