diff --git a/usr.bin/diff/diff.c b/usr.bin/diff/diff.c
--- a/usr.bin/diff/diff.c
+++ b/usr.bin/diff/diff.c
@@ -26,11 +26,11 @@
 #include <err.h>
 #include <errno.h>
 #include <getopt.h>
-#include <stdlib.h>
+#include <limits.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
-#include <limits.h>
 
 #include "diff.h"
 #include "xmalloc.h"
diff --git a/usr.bin/diff/diffdir.c b/usr.bin/diff/diffdir.c
--- a/usr.bin/diff/diffdir.c
+++ b/usr.bin/diff/diffdir.c
@@ -26,10 +26,10 @@
 #include <err.h>
 #include <errno.h>
 #include <fnmatch.h>
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <limits.h>
 #include <unistd.h>
 
 #include "diff.h"
diff --git a/usr.bin/diff/diffreg_new.c b/usr.bin/diff/diffreg_new.c
--- a/usr.bin/diff/diffreg_new.c
+++ b/usr.bin/diff/diffreg_new.c
@@ -15,20 +15,22 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include <sys/types.h>
 #include <sys/capsicum.h>
+#ifndef DIFF_NO_MMAP
 #include <sys/mman.h>
+#endif
 #include <sys/stat.h>
-#include <sys/types.h>
 
 #include <capsicum_helpers.h>
 #include <err.h>
 #include <fcntl.h>
+#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <stdbool.h>
-#include <time.h>
 #include <string.h>
+#include <time.h>
 #include <unistd.h>
 
 #include "diff.h"
@@ -266,10 +268,12 @@
 	diff_result_free(result);
 	diff_data_free(&left);
 	diff_data_free(&right);
+#ifndef DIFF_NO_MMAP
 	if (str1)
 		munmap(str1, st1.st_size);
 	if (str2)
 		munmap(str2, st2.st_size);
+#endif
 	fclose(f1);
 	fclose(f2);