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