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diff --git a/unit-tests/varmod-loop.mk b/unit-tests/varmod-loop.mk
new file mode 100644
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+++ b/unit-tests/varmod-loop.mk
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+# $NetBSD: varmod-loop.mk,v 1.2 2020/08/16 12:30:45 rillig Exp $
+#
+# Tests for the :@var@...${var}...@ variable modifier.
+
+all: mod-loop-varname
+all: mod-loop-resolve
+all: mod-loop-varname-dollar
+all: mod-loop-dollar
+
+# In the :@ modifier, the name of the loop variable can even be generated
+# dynamically.  There's no practical use-case for this, and hopefully nobody
+# will ever depend on this, but technically it's possible.
+# Therefore, in -dL mode, this is forbidden, see lint.mk.
+mod-loop-varname:
+	@echo :${:Uone two three:@${:Ubar:S,b,v,}@+${var}+@:Q}:
+	# ":::" is a very creative variable name, unlikely in practice
+	# The expression ${\:\:\:} would not work since backslashes can only
+	# be escaped in the modifiers, but not in the variable name.
+	@echo :${:U1 2 3:@:::@x${${:U\:\:\:}}y@}:
+	# "@@" is another creative variable name.
+	@echo :${:U1 2 3:@\@\@@x${@@}y@}:
+	# Even "@" works as a variable name since the variable is installed
+	# in the "current" scope, which in this case is the one from the
+	# target.
+	@echo :$@: :${:U1 2 3:@\@@x${@}y@}: :$@:
+	# In extreme cases, even the backslash can be used as variable name.
+	# It needs to be doubled though.
+	@echo :${:U1 2 3:@\\@x${${:Ux:S,x,\\,}}y@}:
+
+# The :@ modifier resolves the variables a little more often than expected.
+# In particular, it resolves _all_ variables from the context, and not only
+# the loop variable (in this case v).
+#
+# The d means direct reference, the i means indirect reference.
+RESOLVE=	${RES1} $${RES1}
+RES1=		1d${RES2} 1i$${RES2}
+RES2=		2d${RES3} 2i$${RES3}
+RES3=		3
+
+mod-loop-resolve:
+	@echo $@:${RESOLVE:@v@w${v}w@:Q}:
+
+# Until 2020-07-20, the variable name of the :@ modifier could end with one
+# or two dollar signs, which were silently ignored.
+# There's no point in allowing a dollar sign in that position.
+mod-loop-varname-dollar:
+	@echo $@:${1 2 3:L:@v$@($v)@:Q}.
+	@echo $@:${1 2 3:L:@v$$@($v)@:Q}.
+	@echo $@:${1 2 3:L:@v$$$@($v)@:Q}.
+
+# Demonstrate that it is possible to generate dollar characters using the
+# :@ modifier.
+#
+# These are edge cases that could have resulted in a parse error as well
+# since the $@ at the end could have been interpreted as a variable, which
+# would mean a missing closing @ delimiter.
+mod-loop-dollar:
+	@echo $@:${:U1:@word@${word}$@:Q}:
+	@echo $@:${:U2:@word@$${word}$$@:Q}:
+	@echo $@:${:U3:@word@$$${word}$$$@:Q}:
+	@echo $@:${:U4:@word@$$$${word}$$$$@:Q}:
+	@echo $@:${:U5:@word@$$$$${word}$$$$$@:Q}:
+	@echo $@:${:U6:@word@$$$$$${word}$$$$$$@:Q}: