diff --git a/case_studies/wookey/loader/GNUmakefile b/case_studies/wookey/loader/GNUmakefile
index 25d30280b5103229cc3c69ab552f572d3c96e05b..b68f3fcb2d28f2b731c5c147b2d8716ab30ca066 100644
--- a/case_studies/wookey/loader/GNUmakefile
+++ b/case_studies/wookey/loader/GNUmakefile
@@ -72,9 +72,10 @@ all: $(TARGETS)
 # 'frama-c-script list-files' can help obtain it
 $(MAIN_TARGET).parse: $(SRCS)
 
-CORES := 1
-WP_CUSTOM :=
-WP_FLAGS= -wp-par $(CORES) -wp-timeout 20 -wp-no-warn-memory-model $(WP_CUSTOM)
+# use path.mk if you want to change the default here
+CORES ?= 1
+WP_CUSTOM ?=
+WP_FLAGS= -wp-par $(CORES) -wp-timeout 20 -wp-no-warn-memory-model -wp-cache update $(WP_CUSTOM)
 
 META_FLAGS= #-meta-keep-proof-files
 OUT_FILE= gen.c
@@ -98,6 +99,9 @@ $(OUT_FILE): $(MAIN_TARGET).parse
 wp: $(OUT_FILE)
 	$(FRAMAC) $(OUT_FILE) -wp $(WP_FLAGS)
 
+prove_gui: $(OUT_FILE)
+	$(FRAMAC_EXEC)-gui $(OUT_FILE) -wp $(WP_FLAGS)
+
 clean::
 	rm -f $(OUT_FILE)
 	rm -rf .frama-c