diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index 8727765add88..4c2e909a2d67 100644
--- a/tools/bpf/bpftool/common.c
+++ b/tools/bpf/bpftool/common.c
@@ -1,7 +1,9 @@
 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 /* Copyright (C) 2017-2018 Netronome Systems, Inc. */
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
diff --git a/tools/bpf/bpftool/iter.c b/tools/bpf/bpftool/iter.c
index f88fdc820d23..a3e6b167153d 100644
--- a/tools/bpf/bpftool/iter.c
+++ b/tools/bpf/bpftool/iter.c
@@ -1,7 +1,9 @@
 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 // Copyright (C) 2020 Facebook
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <unistd.h>
 #include <linux/err.h>
 #include <bpf/libbpf.h>
diff --git a/tools/bpf/bpftool/jit_disasm.c b/tools/bpf/bpftool/jit_disasm.c
index aaf99a0168c9..71cb258ab0ee 100644
--- a/tools/bpf/bpftool/jit_disasm.c
+++ b/tools/bpf/bpftool/jit_disasm.c
@@ -11,7 +11,9 @@
  * Licensed under the GNU General Public License, version 2.0 (GPLv2)
  */
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <stdio.h>
 #include <stdarg.h>
 #include <stdint.h>
diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c
index 526a332c48e6..c40e44c938ae 100644
--- a/tools/bpf/bpftool/net.c
+++ b/tools/bpf/bpftool/net.c
@@ -1,7 +1,9 @@
 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 // Copyright (C) 2018 Facebook
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <errno.h>
 #include <fcntl.h>
 #include <stdlib.h>
diff --git a/tools/bpf/bpftool/perf.c b/tools/bpf/bpftool/perf.c
index 226ec2c39052..91743445e4c7 100644
--- a/tools/bpf/bpftool/perf.c
+++ b/tools/bpf/bpftool/perf.c
@@ -2,7 +2,9 @@
 // Copyright (C) 2018 Facebook
 // Author: Yonghong Song <yhs@fb.com>
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index 10ec29cb4598..dbf5489b8fde 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -1,7 +1,9 @@
 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 /* Copyright (C) 2017-2018 Netronome Systems, Inc. */
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <errno.h>
 #include <fcntl.h>
 #include <signal.h>
diff --git a/tools/bpf/bpftool/xlated_dumper.c b/tools/bpf/bpftool/xlated_dumper.c
index 2d9cd6a7b3c8..6fe3134ae45d 100644
--- a/tools/bpf/bpftool/xlated_dumper.c
+++ b/tools/bpf/bpftool/xlated_dumper.c
@@ -1,7 +1,9 @@
 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 /* Copyright (C) 2018 Netronome Systems, Inc. */
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>