diff --git a/src/include/taler_mhd_lib.h b/src/include/taler_mhd_lib.h
index 4b34f41df..7d281662d 100644
--- a/src/include/taler_mhd_lib.h
+++ b/src/include/taler_mhd_lib.h
@@ -96,6 +96,22 @@ MHD_RESULT
 TALER_MHD_can_compress (struct MHD_Connection *connection);
 
 
+/**
+ * Check if @a lang matches the @a language_pattern, and if so with
+ * which preference.
+ * See also: https://tools.ietf.org/html/rfc7231#section-5.3.1
+ *
+ * @param language_pattern a language preferences string
+ *        like "fr-CH, fr;q=0.9, en;q=0.8, *;q=0.1"
+ * @param lang the 2-digit language to match
+ * @return q-weight given for @a lang in @a language_pattern, 1.0 if no weights are given;
+ *         0 if @a lang is not in @a language_pattern
+ */
+double
+TALER_MHD_language_matches (const char *language_pattern,
+                            const char *lang);
+
+
 /**
  * Send JSON object as response.
  *
diff --git a/src/mhd/mhd_legal.c b/src/mhd/mhd_legal.c
index a6c26bbaa..7de189cce 100644
--- a/src/mhd/mhd_legal.c
+++ b/src/mhd/mhd_legal.c
@@ -165,9 +165,9 @@ xmime_matches (const char *accept_pattern,
  * @return q-weight given for @a lang in @a language_pattern, 1.0 if no weights are given;
  *         0 if @a lang is not in @a language_pattern
  */
-static double
-language_matches (const char *language_pattern,
-                  const char *lang)
+double
+TALER_MHD_language_matches (const char *language_pattern,
+                            const char *lang)
 {
   char *p = GNUNET_strdup (language_pattern);
   char *sptr;
@@ -271,10 +271,10 @@ TALER_MHD_reply_legal (struct MHD_Connection *conn,
         if ( (NULL == t) ||
              (! xmime_matches (mime,
                                t->mime_type)) ||
-             (language_matches (lang,
-                                p->language) >
-              language_matches (lang,
-                                t->language) ) )
+             (TALER_MHD_language_matches (lang,
+                                          p->language) >
+              TALER_MHD_language_matches (lang,
+                                          t->language) ) )
           t = p;
       }
     }