diff --git a/make-linux.mk b/make-linux.mk
index bfa416aa0..9f10cf216 100644
--- a/make-linux.mk
+++ b/make-linux.mk
@@ -292,6 +292,7 @@ ifeq ($(ZT_IA32),1)
 	ZT_USE_X64_ASM_ED25519=0
 endif
 
+ZT_SSO_SUPPORTED=0
 ifeq ($(ZT_SSO_SUPPORTED), 1)
 	ifeq ($(ZT_EMBEDDED),)
 		override DEFS+=-DZT_SSO_SUPPORTED=1