diff --git a/tools/fd2inline/Makefile b/tools/fd2inline/Makefile
index 694ce88508..c0a36efecd 100644
--- a/tools/fd2inline/Makefile
+++ b/tools/fd2inline/Makefile
@@ -4,7 +4,7 @@
 include $(TOP)/config/make.cfg
 
 USER_CPPFLAGS := '-DVERSION="1.39"'
-USER_CFLAGS := -Wall -Wstrict-prototypes -g -O2
+USER_CFLAGS := -Wall -Wstrict-prototypes -std=c11 -g -O2
 
 all : $(FD2INLINE)
 
diff --git a/tools/fd2inline/Makefile.in b/tools/fd2inline/Makefile.in
index d1886ae68d..9874db8b38 100755
--- a/tools/fd2inline/Makefile.in
+++ b/tools/fd2inline/Makefile.in
@@ -27,7 +27,7 @@ RANLIB =		@RANLIB@
 AWK =			@AWK@
 DEFS =			@DEFS@
 LIBS =			@LIBS@
-CFLAGS =		$(DEFS) -Wall -Wstrict-prototypes \
+CFLAGS =		$(DEFS) -Wall -Wstrict-prototypes -std=c11 \
 			'-DVERSION="$(VERSION)"' @CFLAGS@
 LDFLAGS =		@LDFLAGS@
 
diff --git a/tools/fd2inline/fd2inline.c b/tools/fd2inline/fd2inline.c
index caa56e320d..b1b072e3cd 100644
--- a/tools/fd2inline/fd2inline.c
+++ b/tools/fd2inline/fd2inline.c
@@ -30,6 +30,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <strings.h>
 
 /******************************************************************************
  * The program has a few sort of class definitions, which are the result of