diff --git a/draw.c b/draw.c
index f0600f23..7e3aff4f 100644
--- a/draw.c
+++ b/draw.c
@@ -39,13 +39,14 @@ extern awesome_t globalconf;
 /** Convert text from any charset to UTF-8 using iconv.
  * \param iso The ISO string to convert.
  * \param len The string size.
- * \return NULL if error, otherwise pointer to the new converted string.
+ * \param dest The destination pointer. Memory will be allocated, up to you to
+ * free, like any char *.
+ * \param dlen The destination length, can be NULL.
+ * \return True if conversion was done.
  */
-char *
-draw_iso2utf8(const char *iso, size_t len)
+bool
+draw_iso2utf8(const char *iso, size_t len, char **dest, ssize_t *dlen)
 {
-    size_t utf8len;
-    char *utf8, *utf8p;
     static iconv_t iso2utf8 = (iconv_t) -1;
     static int8_t dont_need_convert = -1;
 
@@ -53,7 +54,7 @@ draw_iso2utf8(const char *iso, size_t len)
         dont_need_convert = !a_strcmp(nl_langinfo(CODESET), "UTF-8");
 
     if(!len || dont_need_convert)
-        return NULL;
+        return false;
 
     if(iso2utf8 == (iconv_t) -1)
     {
@@ -66,20 +67,26 @@ draw_iso2utf8(const char *iso, size_t len)
             else
                 warn("unable to convert text: %s", strerror(errno));
 
-            return NULL;
+            return false;
         }
     }
 
-    utf8len = 2 * len + 1;
-    utf8 = utf8p = p_new(char, utf8len);
+    size_t orig_utf8len, utf8len;
+    char *utf8;
+
+    orig_utf8len = utf8len = 2 * len + 1;
+    utf8 = *dest = p_new(char, utf8len);
 
     if(iconv(iso2utf8, (char **) &iso, &len, &utf8, &utf8len) == (size_t) -1)
     {
         warn("text conversion failed: %s", strerror(errno));
-        p_delete(&utf8p);
+        p_delete(dest);
     }
 
-    return utf8p;
+    if(dlen)
+        *dlen = orig_utf8len - utf8len;
+
+    return true;
 }
 
 static xcb_visualtype_t *
diff --git a/draw.h b/draw.h
index 8cad5023..89c3ce25 100644
--- a/draw.h
+++ b/draw.h
@@ -141,18 +141,26 @@ draw_context_wipe(draw_context_t *ctx)
 font_t *draw_font_new(const char *);
 void draw_font_delete(font_t **);
 
-char * draw_iso2utf8(const char *, size_t);
+bool draw_iso2utf8(const char *, size_t, char **, ssize_t *);
 
+/** Convert a string to UTF-8.
+ * \param str The string to convert.
+ * \param len The string length.
+ * \param dest The destination string that will be allocated.
+ * \param dlen The destination string length allocated, can be NULL.
+ * \return True if the conversion happened, false otherwise. In both case, dest
+ * and dlen will have value and dest have to be free().
+ */
 static inline bool
-a_iso2utf8(char **dest, const char *str, ssize_t len)
+a_iso2utf8(const char *str, ssize_t len, char **dest, ssize_t *dlen)
 {
-    char *utf8;
-    if((utf8 = draw_iso2utf8(str, len)))
-    {
-        *dest = utf8;
+    if(draw_iso2utf8(str, len, dest, dlen))
         return true;
-    }
+
     *dest = a_strdup(str);
+    if(dlen)
+        *dlen = len;
+
     return false;
 }
 
diff --git a/property.c b/property.c
index 04a898d7..6156f33a 100644
--- a/property.c
+++ b/property.c
@@ -273,8 +273,9 @@ property_update_wm_name(client_t *c)
 
     p_delete(&c->name);
 
-    if((utf8 = draw_iso2utf8(name, len)))
-        c->name = utf8;
+    /* if no conversion needed, just point to name */
+    if(draw_iso2utf8(name, len, &utf8, NULL))
+        p_delete(&name);
     else
         c->name = name;
 
@@ -298,8 +299,8 @@ property_update_wm_icon_name(client_t *c)
 
     p_delete(&c->icon_name);
 
-    if((utf8 = draw_iso2utf8(name, len)))
-        c->icon_name = utf8;
+    if(draw_iso2utf8(name, len, &utf8, NULL))
+        p_delete(&name);
     else
         c->icon_name = name;
 
diff --git a/tag.c b/tag.c
index cf65a46a..55f2b139 100644
--- a/tag.c
+++ b/tag.c
@@ -54,7 +54,7 @@ tag_new(const char *name, ssize_t len)
     tag_t *tag;
 
     tag = p_new(tag_t, 1);
-    a_iso2utf8(&tag->name, name, len);
+    a_iso2utf8(name, len, &tag->name, NULL);
 
     /* to avoid error */
     tag->screen = SCREEN_UNDEF;
@@ -357,7 +357,7 @@ luaA_tag_newindex(lua_State *L)
         {
             const char *buf = luaL_checklstring(L, 3, &len);
             p_delete(&(*tag)->name);
-            a_iso2utf8(&(*tag)->name, buf, len);
+            a_iso2utf8(buf, len, &(*tag)->name, NULL);
         }
         break;
       case A_TK_SCREEN:
diff --git a/widgets/textbox.c b/widgets/textbox.c
index f5483a31..dd3236cc 100644
--- a/widgets/textbox.c
+++ b/widgets/textbox.c
@@ -30,7 +30,7 @@ typedef struct
     /** Textbox text */
     char *text;
     /** Textbox text length */
-    size_t len;
+    ssize_t len;
     /** Textbox width */
     int width;
     /** Extents */
@@ -244,15 +244,16 @@ luaA_textbox_newindex(lua_State *L, awesome_token_t token)
             draw_parser_data_init(&d->pdata);
             p_delete(&d->text);
 
-            /* re-init */
-            d->len = len;
             if(buf)
             {
-                a_iso2utf8(&d->text, buf, len);
+                a_iso2utf8(buf, len, &d->text, &d->len);
                 d->extents = draw_text_extents(globalconf.font, d->text, d->len, &d->pdata);
             }
             else
+            {
+                d->len = 0;
                 p_clear(&d->extents, 1);
+            }
         }
         break;
       case A_TK_WIDTH: