diff --git a/tests/playground/Makefile b/tests/playground/Makefile
index 118adbdfcb..e53ba77a39 100644
--- a/tests/playground/Makefile
+++ b/tests/playground/Makefile
@@ -12,11 +12,13 @@ OCAML_FLAGS = -O3
 
 ## IMPLEMENTATION
 
+CROSS_INPUTS = $(foreach bench,$(CROSS_BENCHES), $(foreach cat, $(CROSS_CATS), $(bench)$(cat)))
+
 LEAN_BIN ?= ../../bin
 GHC ?= ghc
 OCAML ?= ocamlopt.opt
 
-.PRECIOUS: %.lean.out %.hs.out %.ml.out bench/%
+.SECONDARY: $(CROSS_INPUTS:%=%.out) $(CROSS_INPUTS:%=bench/%.bench)
 .DELETE_ON_ERROR:
 
 all: report_cross.csv
@@ -33,25 +35,25 @@ all: report_cross.csv
 # x.gcc.lean. This also avoids conflicts between intermediate
 # files of the two binaries.
 %.gcc.lean.out: LEAN_BIN = $(LEAN_GCC_BIN)
-%.gcc.lean: %.lean; ln $< $@
+%.gcc.lean: %.lean; ln -f $< $@
 
 %.hs.out: %.hs
 	$(GHC) $(GHC_FLAGS) -rtsopts $< -o $@
 %.llvm.hs.out: GHC_FLAGS += -fllvm
-%.llvm.hs: %.hs; ln $< $@
+%.llvm.hs: %.hs; ln -f $< $@
 
-binarytrees.hs: binarytrees.ghc-6.hs; ln $< $@
+binarytrees.hs: binarytrees.ghc-6.hs; ln -f $< $@
 # NOTE: changed `-N4` rtsopt to `-N` to be less system-dependent
 binarytrees%hs.out: GHC_FLAGS += --make -O2 -XBangPatterns -dynamic -threaded -rtsopts -with-rtsopts='-N -K128M -H'
 
 %.ml.out: %.ml
 	$(OCAML) $(OCAML_FLAGS) $< -o $@
 %.gc.ml.out: OCAML_FLAGS += -runtime-variant i
-%.gc.ml: %.ml; ln $< $@
+%.gc.ml: %.ml; ln -f $< $@
 %.flambda.ml.out: OCAML = $(OCAML_FLAMBDA)
-%.flambda.ml: %.ml; ln $< $@
+%.flambda.ml: %.ml; ln -f $< $@
 
-binarytrees.ml: binarytrees.ocaml-2.ml; ln $< $@
+binarytrees.ml: binarytrees.ocaml-2.ml; ln -f $< $@
 binarytrees%ml.out: OCAML_FLAGS += -noassert -unsafe -fPIC -nodynlink -inline 100 -O3 unix.cmxa
 
 bench:
@@ -74,7 +76,7 @@ bench/%gc.ml.bench: %gc.ml.out | bench
 bench/binarytrees.gc.ml.bench:
 	touch $@
 
-bench_cross: $(foreach bench,$(CROSS_BENCHES), $(foreach cat, $(CROSS_CATS), bench/$(bench)$(cat).bench))
+bench_cross: $(CROSS_INPUTS:%=bench/%.bench)
 
 # yes.
 space = $() $()