Index: darktable-2.4.0rc2~git33.5175e5ed8/src/common/exif.cc
===================================================================
--- darktable-2.4.0rc2~git33.5175e5ed8.orig/src/common/exif.cc
+++ darktable-2.4.0rc2~git33.5175e5ed8/src/common/exif.cc
@@ -175,6 +175,13 @@ static bool dt_exif_read_xmp_tag(Exiv2::
 }
 #define FIND_XMP_TAG(key) dt_exif_read_xmp_tag(xmpData, &pos, key)
 
+#if ! GLIB_CHECK_VERSION(2,40,0)
+static gboolean _str_is_ascii(const char *str)
+{
+  while(*str) if((guchar)*str++ >= 0x80) return FALSE;
+  return TRUE;
+}
+#endif
 
 // FIXME: according to http://www.exiv2.org/doc/classExiv2_1_1Metadatum.html#63c2b87249ba96679c29e01218169124
 // there is no need to pass xmpData
@@ -1294,7 +1301,11 @@ int dt_exif_read_blob(uint8_t **buf, con
       if(res != NULL)
       {
         char *desc = (char *)res->data;
+#if GLIB_CHECK_VERSION(2,40,0)
         if(g_str_is_ascii(desc))
+#else
+        if(_str_is_ascii(desc))
+#endif
           exifData["Exif.Image.ImageDescription"] = desc;
         else
           exifData["Exif.Photo.UserComment"] = desc;