--- a/extensions/GNUmakefile.in
+++ b/extensions/GNUmakefile.in
@@ -40,9 +40,24 @@
 pfx_build_mod := $(filter-out @blacklist_modules@,${pfx_build_mod})
 pf4_build_mod := $(filter-out @blacklist_modules@,${pf4_build_mod})
 pf6_build_mod := $(filter-out @blacklist_modules@,${pf6_build_mod})
-pfx_objs      := $(patsubst %,libxt_%.o,${pfx_build_mod})
-pf4_objs      := $(patsubst %,libipt_%.o,${pf4_build_mod})
-pf6_objs      := $(patsubst %,libip6t_%.o,${pf6_build_mod})
+
+ifdef BUILTIN_MODULES
+pfx_build_static := $(filter $(BUILTIN_MODULES),${pfx_build_mod})
+pf4_build_static := $(filter $(BUILTIN_MODULES),${pf4_build_mod})
+pf6_build_static := $(filter $(BUILTIN_MODULES),${pf6_build_mod})
+else
+@ENABLE_STATIC_TRUE@ pfx_build_static := $(pfx_build_mod)
+@ENABLE_STATIC_TRUE@ pf4_build_static := $(pf4_build_mod)
+@ENABLE_STATIC_TRUE@ pf6_build_static := $(pf6_build_mod)
+endif
+
+pfx_build_mod := $(filter-out $(pfx_build_static),$(pfx_build_mod))
+pf4_build_mod := $(filter-out $(pf4_build_static),$(pf4_build_mod))
+pf6_build_mod := $(filter-out $(pf6_build_static),$(pf6_build_mod))
+
+pfx_objs      := $(patsubst %,libxt_%.o,${pfx_build_static})
+pf4_objs      := $(patsubst %,libipt_%.o,${pf4_build_static})
+pf6_objs      := $(patsubst %,libip6t_%.o,${pf6_build_static})
 pfx_solibs    := $(patsubst %,libxt_%.so,${pfx_build_mod})
 pf4_solibs    := $(patsubst %,libipt_%.so,${pf4_build_mod})
 pf6_solibs    := $(patsubst %,libip6t_%.so,${pf6_build_mod})
@@ -54,10 +69,10 @@
 targets := libext4.a libext6.a matches4.man matches6.man \
            targets4.man targets6.man
 targets_install :=
-@ENABLE_STATIC_TRUE@ libext4_objs := ${pfx_objs} ${pf4_objs}
-@ENABLE_STATIC_TRUE@ libext6_objs := ${pfx_objs} ${pf6_objs}
-@ENABLE_STATIC_FALSE@ targets += ${pfx_solibs} ${pf4_solibs} ${pf6_solibs}
-@ENABLE_STATIC_FALSE@ targets_install += ${pfx_solibs} ${pf4_solibs} ${pf6_solibs}
+libext4_objs := ${pfx_objs} ${pf4_objs}
+libext6_objs := ${pfx_objs} ${pf6_objs}
+targets += ${pfx_solibs} ${pf4_solibs} ${pf6_solibs}
+targets_install := $(strip ${targets_install} ${pfx_solibs} ${pf4_solibs} ${pf6_solibs})
 
 .SECONDARY:
 
@@ -107,8 +122,8 @@
 libext6.a: initext6.o ${libext6_objs}
 	${AM_VERBOSE_AR} ${AR} crs $@ $^;
 
-initext_func  := $(addprefix xt_,${pfx_build_mod}) $(addprefix ipt_,${pf4_build_mod})
-initext6_func := $(addprefix xt_,${pfx_build_mod}) $(addprefix ip6t_,${pf6_build_mod})
+initext_func  := $(addprefix xt_,${pfx_build_static}) $(addprefix ipt_,${pf4_build_static})
+initext6_func := $(addprefix xt_,${pfx_build_static}) $(addprefix ip6t_,${pf6_build_static})
 
 .initext4.dd: FORCE
 	@echo "${initext_func}" >$@.tmp; \
