diff -Naur zstd-1.4.5.orig/lib/Makefile zstd-1.4.5/lib/Makefile

--- zstd-1.4.5.orig/lib/Makefile	2020-05-22 05:04:00.000000000 +0000

+++ zstd-1.4.5/lib/Makefile	2020-05-25 14:11:28.947300726 +0000

@@ -220,13 +220,14 @@

 .PHONY: lib

 lib : libzstd.a libzstd

-.PHONY: lib-mt

+# note : do not define lib-mt or lib-release as .PHONY

+# make does not consider implicit pattern rule for .PHONY target

+

 %-mt : CPPFLAGS += -DZSTD_MULTITHREAD

 %-mt : LDFLAGS  += -pthread

 %-mt : %

 	@echo multi-threading build completed

-.PHONY: lib-release

 %-release : DEBUGFLAGS :=

 %-release : %

 	@echo release build completed