diff --git a/Makefile b/Makefile
index 12defd4c9..dd3d5203f 100644
--- a/Makefile
+++ b/Makefile
@@ -734,6 +734,7 @@ ifeq ($(uname_S),SunOS)
 	NO_MKSTEMPS = YesPlease
 	NO_REGEX = YesPlease
 	NO_EXTERNAL_GREP = YesPlease
+	THREADED_DELTA_SEARCH = YesPlease
 	ifeq ($(uname_R),5.7)
 		NEEDS_RESOLV = YesPlease
 		NO_IPV6 = YesPlease