diff --git a/ppn2ocr b/ppn2ocr
index 140a8a3..bfcc7da 100755
--- a/ppn2ocr
+++ b/ppn2ocr
@@ -39,6 +39,19 @@ def oai_mets(ppn):
     return mets
 
 
+def iiif_url_for_sbb_url(sbb_url, ppn, size, format):
+    """
+    Construct an IIIF URL from a dms or an IIIF URL.
+
+    This function exists as long as dms URL exist (or as long as we may need to
+    rewrite IIIF URLs for a different size)
+    """
+    if "/dms/" in sbb_url:
+        return iiif_url_for_dms_url(sbb_url, ppn, size, format)
+    else:
+        return iiif_url_for_iiif_url(sbb_url, ppn, size, format)
+
+
 def iiif_url_for_dms_url(dms_url, ppn, size, format):
     """
     Construct an IIIF URL from a dms URL.
@@ -59,6 +72,24 @@ def iiif_url_for_dms_url(dms_url, ppn, size, format):
     return iiif_url
 
 
+def iiif_url_for_iiif_url(iiif_url, ppn, size, format):
+    """
+    Construct an IIIF URL from an already existing IIIF URL.
+    """
+    if ppn not in iiif_url:
+        raise ValueError(f"Unexpected URL {iiif_url}")
+    m = re.search(rf'/dc/{ppn}-([0-9]+)/', iiif_url)
+    if m:
+        page_num = m.group(1)
+    else:
+        raise ValueError(f"Unexpected URL {iiif_url}")
+    iiif_identifier = f'{ppn}-{page_num}'
+    iiif_quality = 'default'
+    iiif_url = f'https://content.staatsbibliothek-berlin.de/dc/{iiif_identifier}/full/{size}/0/{iiif_quality}.{format}'
+
+    return iiif_url
+
+
 def remove_file_grp(mets, use):
     for bad_fileid in mets.xpath(f'//mets:fileGrp[@USE="{use}"]/mets:file/@ID', namespaces=XMLNS):
         for bad in mets.xpath(f'//mets:fptr[@FILEID="{bad_fileid}"]', namespaces=XMLNS):
@@ -134,7 +165,7 @@ def make_workspace(ppn, workspace):
         # XXX Need to fumble around with the URL for now
         flocat = f.find(f".//{{{XMLNS['mets']}}}FLocat")
         old_url = flocat.attrib[f"{{{XMLNS['xlink']}}}href"]
-        url_iiif_full = iiif_url_for_dms_url(old_url, ppn, 'full', format_)
+        url_iiif_full = iiif_url_for_sbb_url(old_url, ppn, 'full', format_)
         flocat.attrib[f"{{{XMLNS['xlink']}}}href"] = url_iiif_full
 
     mets.find('//mets:fileSec', namespaces=XMLNS).append(file_grp_best)