diff --git a/Make.mk b/Make.mk
index 628a99ef..1e2f01f2 100644
--- a/Make.mk
+++ b/Make.mk
@@ -61,9 +61,9 @@ topics := $(patsubst %.t,%,$(notdir $(tsrc)))
 info := $(topics) $(subjects) all TOP
 subjects.html := $(addprefix info.html/, $(addsuffix .html, $(subjects)))
 topics.html := $(addprefix info.html/, $(addsuffix .html, $(topics)))
-scripts = $(srcdir)/src/scripts
-depcomp = $(SHELL) $(srcdir)/depcomp
-tarball = $(SHELL) $(scripts)/tarball
+scripts := $(srcdir)/src/scripts
+depcomp := $(SHELL) $(srcdir)/depcomp
+tarball := $(SHELL) $(scripts)/tarball
 econfig := $(sysconfdir)/empire/econfig
 gamedir := $(localstatedir)/empire
 builtindir := $(datadir)/empire/builtin