diff --git a/src/python/jw/pkg/cmds/projects/lib/templates.py b/src/python/jw/pkg/cmds/projects/lib/templates.py
index 3df12aa5..bc9bf23c 100644
--- a/src/python/jw/pkg/cmds/projects/lib/templates.py
+++ b/src/python/jw/pkg/cmds/projects/lib/templates.py
@@ -7,7 +7,7 @@ ListDict: TypeAlias = dict[str, list[str]]
 StrDict: TypeAlias = dict[str, str]
 RenderValues: TypeAlias = ListDict | StrDict | TupleList
 
-def is_str_dict(values: RenderValues) -> TypeGuard[StrDict]:
+def is_str_dict(values: object) -> TypeGuard[StrDict]:
     if not isinstance(values, dict):
         return False
     for key, val in values.items():
@@ -17,7 +17,7 @@ def is_str_dict(values: RenderValues) -> TypeGuard[StrDict]:
             return False
     return True
 
-def is_list_dict(values: RenderValues) -> TypeGuard[ListDict]:
+def is_list_dict(values: object) -> TypeGuard[ListDict]:
     if not isinstance(values, dict):
         return False
     for key, val in values.items():
@@ -32,7 +32,7 @@ def is_list_dict(values: RenderValues) -> TypeGuard[ListDict]:
                 return False
     return True
 
-def is_tuple_list(values: RenderValues) -> TypeGuard[TupleList]:
+def is_tuple_list(values: object) -> TypeGuard[TupleList]:
     if not isinstance(values, list):
         return False
     for item in values:
@@ -46,7 +46,7 @@ def is_tuple_list(values: RenderValues) -> TypeGuard[TupleList]:
             return False
     return True
 
-def render_values_to_list_dict(values: RenderValues) -> ListDict:
+def render_values_to_list_dict(values: object) -> ListDict:
 
     def __tuple_list_to_dict(src: TupleList) -> ListDict:
         ret: ListDict = {}
@@ -56,7 +56,12 @@ def render_values_to_list_dict(values: RenderValues) -> ListDict:
         return ret
 
     if is_list_dict(values):
-        return values
+        ret: ListDict = {}
+        for key, val in values.items():
+            # -- A string value is treated as a list with a single element;
+            # merging it unconverted would split it into characters
+            ret[key] = val if isinstance(val, list) else [val]
+        return ret
     if is_tuple_list(values):
         return __tuple_list_to_dict(values)
     raise Exception('Unsupported template value layout')
diff --git a/test/unit/python/jw/pkg/cmds/Makefile b/test/unit/python/jw/pkg/cmds/Makefile
new file mode 100644
index 00000000..f817ac8c
--- /dev/null
+++ b/test/unit/python/jw/pkg/cmds/Makefile
@@ -0,0 +1,4 @@
+TOPDIR = ../../../../../..
+
+include $(TOPDIR)/make/proj.mk
+include $(JWBDIR)/make/dirs.mk
diff --git a/test/unit/python/jw/pkg/cmds/projects/Makefile b/test/unit/python/jw/pkg/cmds/projects/Makefile
new file mode 100644
index 00000000..c87020cb
--- /dev/null
+++ b/test/unit/python/jw/pkg/cmds/projects/Makefile
@@ -0,0 +1,4 @@
+TOPDIR = ../../../../../../..
+
+include $(TOPDIR)/make/proj.mk
+include $(JWBDIR)/make/dirs.mk
diff --git a/test/unit/python/jw/pkg/cmds/projects/lib/Makefile b/test/unit/python/jw/pkg/cmds/projects/lib/Makefile
new file mode 100644
index 00000000..3b96da8e
--- /dev/null
+++ b/test/unit/python/jw/pkg/cmds/projects/lib/Makefile
@@ -0,0 +1,4 @@
+TOPDIR = ../../../../../../../..
+
+include $(TOPDIR)/make/proj.mk
+include $(JWBDIR)/make/dirs.mk
diff --git a/test/unit/python/jw/pkg/cmds/projects/lib/templates/Makefile b/test/unit/python/jw/pkg/cmds/projects/lib/templates/Makefile
new file mode 100644
index 00000000..6a0e35b2
--- /dev/null
+++ b/test/unit/python/jw/pkg/cmds/projects/lib/templates/Makefile
@@ -0,0 +1,8 @@
+TOPDIR = ../../../../../../../../..
+
+include $(TOPDIR)/make/proj.mk
+include $(JWBDIR)/make/py-run.mk
+
+all:
+
+test: run
diff --git a/test/unit/python/jw/pkg/cmds/projects/lib/templates/test.py b/test/unit/python/jw/pkg/cmds/projects/lib/templates/test.py
new file mode 100644
index 00000000..46400ddd
--- /dev/null
+++ b/test/unit/python/jw/pkg/cmds/projects/lib/templates/test.py
@@ -0,0 +1,73 @@
+from jw.pkg.cmds.projects.lib.templates import (
+    is_list_dict,
+    is_str_dict,
+    is_tuple_list,
+    merge_values,
+    render_values_to_list_dict,
+)
+
+# -- Type guards --
+
+assert is_str_dict({'a': 'x', 'b': 'y'})
+assert not is_str_dict({'a': ['x']})
+assert not is_str_dict({'a': 1})
+assert not is_str_dict([('a', 'x')])
+
+assert is_list_dict({'a': ['x'], 'b': ['y']})
+# A string value is a legitimate list-dict value, too
+assert is_list_dict({'a': ['x'], 'b': 'y'})
+assert not is_list_dict({'a': 1})
+assert not is_list_dict({'a': ['x', 1]})
+assert not is_list_dict([('a', 'x')])
+
+assert is_tuple_list([('a', 'x'), ('b', 'y')])
+assert not is_tuple_list([('a', 'x', 'y')])
+assert not is_tuple_list([('a', 1)])
+assert not is_tuple_list(['a'])
+
+# -- render_values_to_list_dict --
+
+# A list of lists passes through unchanged
+assert render_values_to_list_dict({'a': ['x', 'y']}) == {'a': ['x', 'y']}
+
+# String values are normalized to single-element lists, not split up
+assert render_values_to_list_dict({'a': 'xyz'}) == {'a': ['xyz']}
+assert render_values_to_list_dict({'a': ['x'], 'b': 'y'}) == {'a': ['x'], 'b': ['y']}
+
+# Tuple lists are folded into a dict of lists
+assert render_values_to_list_dict([('a', 'x'), ('a', 'y'), ('b', 'z')]) == {
+    'a': ['x', 'y'],
+    'b': ['z'],
+}
+
+# Unsupported layouts raise
+try:
+    render_values_to_list_dict({'a': 1})
+    assert False, 'Should have raised'
+except Exception:
+    pass
+
+# -- merge_values --
+
+# String values are merged as whole strings, not character by character
+assert merge_values({
+    'prefix': '/usr', 'name': 'jw-pkg'
+}) == {
+    'prefix': ['/usr'],
+    'name': ['jw-pkg'],
+}
+
+# Values for the same key are appended in order
+assert merge_values({'a': ['x']}, {'a': ['y']}) == {'a': ['x', 'y']}
+assert merge_values({'a': 'x'}, {'a': 'y'}) == {'a': ['x', 'y']}
+
+# All three layouts can be mixed
+assert merge_values(
+    {'a': ['x']},
+    {'a': 'y'},
+    [('a', 'z'), ('b', 'w')],
+) == {
+    'a': ['x', 'y', 'z'], 'b': ['w']
+}
+
+print('All templates merge tests passed')