diff --git a/org_mode_samples/exit_matcher_investigation/Makefile b/org_mode_samples/exit_matcher_investigation/Makefile
index 96ec59d..c47a86c 100644
--- a/org_mode_samples/exit_matcher_investigation/Makefile
+++ b/org_mode_samples/exit_matcher_investigation/Makefile
@@ -4,7 +4,6 @@ SHELL := bash
 .DELETE_ON_ERROR:
 MAKEFLAGS += --warn-undefined-variables
 MAKEFLAGS += --no-builtin-rules
-OUT=out
 SRCFILES := $(wildcard *.org)
 OUTFILES := $(patsubst %.org,%.tree.txt,$(SRCFILES))
 
diff --git a/org_mode_samples/plain_lists/Makefile b/org_mode_samples/plain_lists/Makefile
index 61a8d82..c47a86c 100644
--- a/org_mode_samples/plain_lists/Makefile
+++ b/org_mode_samples/plain_lists/Makefile
@@ -4,7 +4,8 @@ SHELL := bash
 .DELETE_ON_ERROR:
 MAKEFLAGS += --warn-undefined-variables
 MAKEFLAGS += --no-builtin-rules
-OUT=out
+SRCFILES := $(wildcard *.org)
+OUTFILES := $(patsubst %.org,%.tree.txt,$(SRCFILES))
 
 ifeq ($(origin .RECIPEPREFIX), undefined)
   $(error This Make does not support .RECIPEPREFIX. Please use GNU Make 4.0 or later)
@@ -12,11 +13,11 @@ endif
 .RECIPEPREFIX = >
 
 .PHONY: all
-all: paragraphs.tree.txt nested_paragraphs.tree.txt
+all: $(OUTFILES)
 
 .PHONY: clean
 clean:
-> rm -rf *.tree.txt
+> rm -rf $(OUTFILES)
 
 %.tree.txt: %.org ../common.el ../dump_org_ast.bash
 > ../dump_org_ast.bash $< $@