diff --git a/Makefile b/Makefile
index 12d09d0..ca5b5f5 100644
--- a/Makefile
+++ b/Makefile
@@ -1,3 +1,4 @@
+INTERPRETER := ruby
 GENERATOR='./generate.rb'
 
 MAKE_TARGETS=$(patsubst dates/%.yaml, dates/%/ALL, $(wildcard dates/*.yaml))
@@ -12,7 +13,8 @@ clean:
 
 dates/%/Makefile: dates/%.yaml $(wildcard decks/*.yaml)
 	mkdir -p $(shell dirname $@)
-	$(GENERATOR) $< $(shell dirname $@) || printf "\033[1;31minterpreter or script missing\033[0m\n"
+	command -v $(INTERPRETER) || (printf "Could not find '%s' – Please install or add it to PATH!\n" $(INTERPRETER); exit 1)
+	$(INTERPRETER) $(GENERATOR) $< $(shell dirname $@)
 
 dates/%/ALL: dates/%/Makefile
 	$(MAKE) -C $(shell dirname $@)