diff --git a/Doc/source/designspaceLib/readme.rst b/Doc/source/designspaceLib/readme.rst
index 06bf46ffc..cd772af32 100644
--- a/Doc/source/designspaceLib/readme.rst
+++ b/Doc/source/designspaceLib/readme.rst
@@ -277,7 +277,8 @@ AxisDescriptor object
    dicts. MutatorMath + Varlib.
 -  ``labelNames``: dict. When defining a non-registered axis, it will be
    necessary to define user-facing readable names for the axis. Keyed by
-   xml:lang code. Varlib.
+   xml:lang code. Values are required to be ``unicode`` strings, even if
+   they only contain ASCII characters.
 -  ``minimum``: number. The minimum value for this axis in user space.
    MutatorMath + Varlib.
 -  ``maximum``: number. The maximum value for this axis in user space.
diff --git a/Doc/source/designspaceLib/scripting.rst b/Doc/source/designspaceLib/scripting.rst
index 2bd4a0a18..5a17816ad 100644
--- a/Doc/source/designspaceLib/scripting.rst
+++ b/Doc/source/designspaceLib/scripting.rst
@@ -70,7 +70,7 @@ readable names for this axis if this is not an axis that is registered
 by OpenType. Think "The label next to the slider". The attribute is a
 dictionary. The key is the `xml language
 tag <https://www.w3.org/International/articles/language-tags/>`__, the
-value is a utf-8 string with the name. Whether or not this attribute is
+value is a ``unicode`` string with the name. Whether or not this attribute is
 used depends on the font building tool, the operating system and the
 authoring software. This, at least, is the place to record it.