diff --git a/guix/ui.scm b/guix/ui.scm
index 4a3630f242..67dd062a34 100644
--- a/guix/ui.scm
+++ b/guix/ui.scm
@@ -803,7 +803,10 @@ converted to a space; sequences of more than one line break are preserved."
 
 (define (texi->plain-text str)
   "Return a plain-text representation of texinfo fragment STR."
-  (stexi->plain-text (texi-fragment->stexi str)))
+  ;; 'texi-fragment->stexi' uses a string port so make sure it's a
+  ;; Unicode-capable one (see <http://bugs.gnu.org/11197>.)
+  (with-fluids ((%default-port-encoding "UTF-8"))
+    (stexi->plain-text (texi-fragment->stexi str))))
 
 (define (package-description-string package)
   "Return a plain-text representation of PACKAGE description field."
diff --git a/tests/ui.scm b/tests/ui.scm
index 25fc709431..bd4c907525 100644
--- a/tests/ui.scm
+++ b/tests/ui.scm
@@ -22,6 +22,7 @@
   #:use-module (guix profiles)
   #:use-module (guix store)
   #:use-module (guix derivations)
+  #:use-module (guix tests)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-19)
@@ -89,6 +90,12 @@ interface, and powerful string processing.")
   (fill-paragraph "First line.
 Second line" 24))
 
+(test-equal "package-description-string vs. Unicode"
+  "b•ll•t\n\n"                                ;see <http://bugs.gnu.org/21536>
+  (with-fluids ((%default-port-encoding "ISO-8859-1"))
+    (package-description-string
+     (dummy-package "foo" (description "b•ll•t")))))
+
 (test-equal "package-specification->name+version+output"
   '(("guile" #f "out")
     ("guile" "2.0.9" "out")