diff --git a/doc/guix.texi b/doc/guix.texi
index a9e1f66492..158261e373 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -33230,7 +33230,15 @@ Enable or disable debug output.
 Enable or disable the addition of iptables rules.
 
 @item @code{environment-variables} (default: @code{()})
-Environment variables to set for dockerd
+List of environment variables to set for @command{dockerd}.
+
+This must be a list of strings where each string has the form
+@samp{@var{key}=@var{value}} as in this example:
+
+@lisp
+(list "LANGUAGE=eo:ca:eu"
+      "TMPDIR=/tmp/dockerd")
+@end lisp
 
 @end table
 @end deftp