diff --git a/boot/syslinux/syslinux.mk b/boot/syslinux/syslinux.mk
index b8f022b189..f938634c35 100644
--- a/boot/syslinux/syslinux.mk
+++ b/boot/syslinux/syslinux.mk
@@ -56,6 +56,9 @@ SYSLINUX_POST_PATCH_HOOKS += SYSLINUX_CLEANUP
 # syslinux build system has no convenient way to pass CFLAGS,
 # and the internal zlib should take precedence so -I shouldn't
 # be used.
+# gcc-15 defaults to -std=gnu23 which introduces build failures.
+# We force "-std=gnu17" for gcc version supporting it. Earlier gcc
+# versions will work, since they are using the older standard.
 # Install in a temporary location that eases final install into
 # images/ (see corresponding command, below).
 # Repeat the target, otherwise syslinux will try to build everything
@@ -65,7 +68,7 @@ define SYSLINUX_BUILD_CMDS
 	$(TARGET_MAKE_ENV) $(MAKE1) \
 		ASCIIDOC_OK=-1 \
 		A2X_XML_OK=-1 \
-		CC="$(TARGET_CC) -std=gnu17" \
+		CC="$(TARGET_CC) $(if $(BR2_TOOLCHAIN_GCC_AT_LEAST_8),-std=gnu17)" \
 		LD="$(TARGET_LD)" \
 		OBJCOPY="$(TARGET_OBJCOPY)" \
 		AS="$(TARGET_AS)" \