diff --git a/Makefile.impls b/Makefile.impls
index 68d1f983..685aadc6 100644
--- a/Makefile.impls
+++ b/Makefile.impls
@@ -24,6 +24,8 @@ matlab_MODE = octave
 python_MODE = python
 # scheme (chibi, kawa, gauche, chicken, sagittarius, cyclone, foment)
 scheme_MODE = chibi
+# sml (polyml, mlton, mosml)
+sml_MODE = polyml
 # wasmtime wasmer lucet wax  node warpy  wace_libc
 wasm_MODE = wasmtime
 
diff --git a/impls/sml/.gitignore b/impls/sml/.gitignore
new file mode 100644
index 00000000..cb5dad85
--- /dev/null
+++ b/impls/sml/.gitignore
@@ -0,0 +1,4 @@
+.smlmode
+.step*
+*.ui
+*.uo
diff --git a/impls/sml/Makefile b/impls/sml/Makefile
index 9ef9d41d..7f4eef1a 100644
--- a/impls/sml/Makefile
+++ b/impls/sml/Makefile
@@ -1,23 +1,56 @@
 STEP_BINS = step0_repl step1_read_print step2_eval step3_env step4_if_fn_do
 
+sml_MODE_DEFAULT = polyml
+sml_MODE_CONFIG  = .smlmode
+
+ifeq ($(sml_MODE),)
+sml_MODE = $(sml_MODE_DEFAULT)
+endif
+# some hackery to let Make know if it needs to rebuild when sml_MODE changes
+ifneq ($(sml_MODE),$(shell cat $(sml_MODE_CONFIG) 2> /dev/null))
+$(shell rm $(sml_MODE_CONFIG) 2> /dev/null)
+endif
+
+ifeq ($(sml_MODE),mlton)
+SMLC        = mlton
+SMLCOUTFLAG = -output
+BUILD_FILE  = %.mlb
+build_args  = $1
+endif
+ifeq ($(sml_MODE),mosml)
+SMLC        = mosmlc
+SMLCOUTFLAG = -o
+BUILD_FILE  = %.mlb
+build_args  = -toplevel $(shell grep "\\.sml" $1)
+endif
+ifeq ($(sml_MODE),polyml)
+SMLC        = polyc
+SMLCOUTFLAG = -o
+BUILD_FILE  = .%.poly.sml
+build_args  = $1
+endif
+
 all: $(STEP_BINS)
 
-step0_repl: step0_repl.mlb step0_repl.sml main.sml
-	mlton -output $@ $<
+.%.dep: %.mlb
+	@echo sml-deps -o $@ $<
+	$(eval DEPS := $(shell grep "\\.sml" $<))
+	@echo "$(@:.%.dep=%) $@: $(DEPS)" > $@
 
-step1_read_print: step1_read_print.mlb step1_read_print.sml reader.sml printer.sml types.sml util.sml main.sml
-	mlton -output $@ $<
+include $(STEP_BINS:%=.%.dep)
 
-step2_eval: step2_eval.mlb step2_eval.sml env.sml reader.sml printer.sml types.sml util.sml main.sml
-	mlton -output $@ $<
+.%.poly.sml: %.mlb
+	@echo generate-sml -o $@ $<
+	@grep "\\.sml" $< | grep -v main | xargs printf "use \"%s\";\n" > $@
 
-step3_env: step3_env.mlb step3_env.sml env.sml reader.sml printer.sml types.sml util.sml main.sml
-	mlton -output $@ $<
+# some hackery to let Make track changes in sml_MODE
+$(sml_MODE_CONFIG):
+	@echo $(sml_MODE) > $@
 
-step4_if_fn_do: step4_if_fn_do.mlb step4_if_fn_do.sml core.sml env.sml reader.sml printer.sml types.sml util.sml main.sml
-	mlton -output $@ $<
+$(STEP_BINS): %: $(BUILD_FILE) $(sml_MODE_CONFIG)
+	$(SMLC) $(SMLCOUTFLAG) $@ $(call build_args,$<)
 
 clean:
-	rm -f $(STEP_BINS)
+	rm -f $(STEP_BINS) .*.dep *.ui *.uo .*.poly.sml $(sml_MODE_CONFIG)
 
 .PHONY: all clean