diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile
index f385a4b4a484e36d3262ca154b96dcfd596b7510..b8bd0c4aa02e4d0bae958c2fec0fa492c49ca583 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -48,7 +48,7 @@ obj-$(VDSO64-y)			+= vdso-syms.lds
 # Match symbols in the DSO that look like VDSO*; produce a file of constants.
 #
 sed-vdsosym := -e 's/^00*/0/' \
-	-e 's/^\([0-9a-fA-F]*\) . \(VDSO[a-zA-Z0-9_]*\)$$/\2 = 0x\1;/p'
+	-e 's/^\([[:xdigit:]]*\) . \(VDSO[[:alnum:]_]*\)$$/\2 = 0x\1;/p'
 quiet_cmd_vdsosym = VDSOSYM $@
       cmd_vdsosym = $(NM) $< | sed -n $(sed-vdsosym) | LC_ALL=C sort > $@