diff --git a/ChangeLog.d/fix-redefination_warning_messages_for_GNU_SOURCE.txt b/ChangeLog.d/fix-redefination_warning_messages_for_GNU_SOURCE.txt
new file mode 100644
index 0000000000..b5c26505c2
--- /dev/null
+++ b/ChangeLog.d/fix-redefination_warning_messages_for_GNU_SOURCE.txt
@@ -0,0 +1,5 @@
+Bugfix
+   * Fix issue of redefinition warning messages for _GNU_SOURCE in
+     entropy_poll.c and sha_256.c. There was a build warning during
+     building for linux platform.
+     Resolves #9026
diff --git a/library/entropy_poll.c b/library/entropy_poll.c
index 794ee03a83..611768cd85 100644
--- a/library/entropy_poll.c
+++ b/library/entropy_poll.c
@@ -5,10 +5,12 @@
  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
  */
 
-#if defined(__linux__) || defined(__midipix__) && !defined(_GNU_SOURCE)
+#if defined(__linux__) || defined(__midipix__)
 /* Ensure that syscall() is available even when compiling with -std=c99 */
+#if !defined(_GNU_SOURCE)
 #define _GNU_SOURCE
 #endif
+#endif
 
 #include "common.h"
 
diff --git a/library/sha256.c b/library/sha256.c
index 87889817a4..8b2c34526b 100644
--- a/library/sha256.c
+++ b/library/sha256.c
@@ -44,7 +44,9 @@
 #endif /* defined(__clang__) &&  (__clang_major__ >= 4) */
 
 /* Ensure that SIG_SETMASK is defined when -std=c99 is used. */
+#if !defined(_GNU_SOURCE)
 #define _GNU_SOURCE
+#endif
 
 #include "common.h"