diff --git a/Makefile b/Makefile
index c3b5ed80f8..07dad26d7b 100644
--- a/Makefile
+++ b/Makefile
@@ -119,8 +119,13 @@ oldtest: | nvim build/runtime/doc/tags
 ifeq ($(strip $(TEST_FILE)),)
 	+$(SINGLE_MAKE) -C src/nvim/testdir NVIM_PRG="$(realpath build/bin/nvim)" $(MAKEOVERRIDES)
 else
-	+$(SINGLE_MAKE) -C src/nvim/testdir NVIM_PRG="$(realpath build/bin/nvim)" SCRIPTS= $(MAKEOVERRIDES) $(TEST_FILE)
+	@# Handle TEST_FILE=test_foo{,.res,.vim}.
+	+$(SINGLE_MAKE) -C src/nvim/testdir NVIM_PRG="$(realpath build/bin/nvim)" SCRIPTS= $(MAKEOVERRIDES) $(patsubst %.vim,%,$(patsubst %.res,%,$(TEST_FILE)))
 endif
+# Build oldtest by specifying the relative .vim filename.
+.PHONY: phony_force
+src/nvim/testdir/%.vim: phony_force
+	+$(SINGLE_MAKE) -C src/nvim/testdir NVIM_PRG="$(realpath build/bin/nvim)" SCRIPTS= $(MAKEOVERRIDES) $(patsubst src/nvim/testdir/%.vim,%,$@)
 
 build/runtime/doc/tags helptags: | nvim
 	+$(BUILD_CMD) -C build runtime/doc/tags
@@ -201,10 +206,10 @@ lint: check-single-includes clint lualint _opt_pylint _opt_shlint
 # Generic pattern rules, allowing for `make build/bin/nvim` etc.
 # Does not work with "Unix Makefiles".
 ifeq ($(BUILD_TYPE),Ninja)
-build/%:
+build/%: phony_force
 	$(BUILD_CMD) -C build $(patsubst build/%,%,$@)
 
-$(DEPS_BUILD_DIR)/%:
+$(DEPS_BUILD_DIR)/%: phony_force
 	$(BUILD_CMD) -C $(DEPS_BUILD_DIR) $(patsubst $(DEPS_BUILD_DIR)/%,%,$@)
 endif
 
diff --git a/src/nvim/testdir/Makefile b/src/nvim/testdir/Makefile
index 1e9031e098..6bf070a7e2 100644
--- a/src/nvim/testdir/Makefile
+++ b/src/nvim/testdir/Makefile
@@ -34,22 +34,23 @@ SCRIPTS ?= $(SCRIPTS_DEFAULT)
 
 # Tests using runtest.vim.
 NEW_TESTS_ALOT := test_alot_utf8 test_alot
-NEW_TESTS_IN_ALOT := $(shell sed '/^source/ s/^source //;s/\.vim$$//' test_alot*.vim)
+NEW_TESTS_IN_ALOT := $(shell sed -n '/^source/ s/^source //; s/\.vim$$//p' $(addsuffix .vim,$(NEW_TESTS_ALOT)))
+NEW_TESTS_IN_ALOT_LATIN := $(shell sed -n '/^source/ s/^source //; s/\.vim$$//p' test_alot_latin.vim)
 # Ignored tests.
 # test_alot_latin: Nvim does not allow setting encoding.
 # test_autochdir: ported to Lua, but kept for easier merging.
 # test_eval_func: used as include in old-style test (test_eval.in).
 # test_listlbr: Nvim does not allow setting encoding.
 # test_largefile: uses too much resources to run on CI.
-NEW_TESTS_IGNORE := $(NEW_TESTS_IN_ALOT) $(NEW_TESTS_ALOT) \
-  test_alot_latin \
+NEW_TESTS_IGNORE := \
+  test_alot_latin $(NEW_TESTS_IN_ALOT_LATIN) \
   test_autochdir \
   test_eval_func \
   test_listlbr \
   test_largefile \
 
-NEW_TESTS ?= $(sort $(filter-out $(NEW_TESTS_IGNORE),$(basename $(notdir $(wildcard test_*.vim))))) $(NEW_TESTS_ALOT)
-NEW_TESTS_RES ?= $(addsuffix .res,$(NEW_TESTS))
+NEW_TESTS := $(sort $(basename $(notdir $(wildcard test_*.vim))))
+NEW_TESTS_RES := $(addsuffix .res,$(filter-out $(NEW_TESTS_ALOT) $(NEW_TESTS_IN_ALOT) $(NEW_TESTS_IGNORE),$(NEW_TESTS)) $(NEW_TESTS_ALOT))
 
 
 ifdef VALGRIND_GDB
@@ -114,7 +115,7 @@ fixff:
 	  dotest.in
 
 # Execute an individual new style test, e.g.:
-# make test_largefile
+# 	make test_largefile
 $(NEW_TESTS):
 	rm -f $@.res test.log messages
 	@MAKEFLAGS=--no-print-directory $(MAKE) -f Makefile $@.res
diff --git a/test/README.md b/test/README.md
index 2cee7da009..a6e9080a40 100644
--- a/test/README.md
+++ b/test/README.md
@@ -77,11 +77,14 @@ To run all legacy Vim tests:
 
     make oldtest
 
-To run a *single* legacy test set `TEST_FILE`, for example:
+To run a *single* legacy test file you can use either:
 
-    TEST_FILE=test_syntax.res make oldtest
+    make oldtest TEST_FILE=test_syntax.vim
+
+or:
+
+    make src/nvim/testdir/test_syntax.vim
 
-- The `.res` extension (instead of `.vim`) is required.
 - Specify only the test file name, not the full path.