diff --git a/base/glibc/glibc.conf b/base/glibc/glibc.conf
index 88d2b123b..902bc8bfa 100644
--- a/base/glibc/glibc.conf
+++ b/base/glibc/glibc.conf
@@ -77,7 +77,10 @@ if [ $SDECFG_PKG_GLIBC_TLS = 1 ]; then
 					tls_arch=x86_64
 					;;
 			esac
-			var_append configcache ' ' "libc_cv_${tls_arch}_tls=yes"
+			if [ -n "$tls_arch" ]; then
+				var_append configcache ' ' \
+					"libc_cv_${tls_arch}_tls=yes"
+			fi
 		else
 			# extra configure options for cross stage
 			var_append extraconfopt " " "--with-tls"