diff --git a/pica2mods-xslt/src/main/resources/xsl/ubr/pica2mods-ubr-POSTPROCESSING.xsl b/pica2mods-xslt/src/main/resources/xsl/ubr/pica2mods-ubr-POSTPROCESSING.xsl
index c73327ba..e437386e 100644
--- a/pica2mods-xslt/src/main/resources/xsl/ubr/pica2mods-ubr-POSTPROCESSING.xsl
+++ b/pica2mods-xslt/src/main/resources/xsl/ubr/pica2mods-ubr-POSTPROCESSING.xsl
@@ -203,7 +203,7 @@
       <xsl:if test="$parent/*">
         <!-- 4950 (recordIdentifier from PURL / URL, ein eigenes Feld) -->
         <xsl:for-each select="$parent/p:datafield[@tag='017C']/p:subfield[@code='u'][contains(., '://purl.uni-rostock.de/')][1]">
-          <mods:recordIdentifier source="DE-28">{substring-after(substring(.,9), '/')}</mods:recordIdentifier>
+          <mods:recordIdentifier source="DE-28">{translate(substring-after(substring(.,9), '/'),'/','_')}</mods:recordIdentifier>
         </xsl:for-each>
         <xsl:for-each select="$parent/p:datafield[@tag='004U']/p:subfield[@code='0' and contains(., 'gbv:519')][1]"> 
           <mods:recordIdentifier source="DE-519">dbhsnb/{substring(.,20,string-length(.)-19-2)}</mods:recordIdentifier>
diff --git a/pica2mods-xslt/src/main/resources/xsl/ubr/pica2mods-ubr-recordInfo.xsl b/pica2mods-xslt/src/main/resources/xsl/ubr/pica2mods-ubr-recordInfo.xsl
index a5886bb2..7461e033 100644
--- a/pica2mods-xslt/src/main/resources/xsl/ubr/pica2mods-ubr-recordInfo.xsl
+++ b/pica2mods-xslt/src/main/resources/xsl/ubr/pica2mods-ubr-recordInfo.xsl
@@ -27,7 +27,7 @@
     <mods:recordInfo>
       <xsl:for-each
         select="./p:datafield[@tag='017C']/p:subfield[@code='u' and contains(., '://purl.uni-rostock.de')][1]"> <!-- 4950 URL (kein eigenes Feld) -->
-        <mods:recordIdentifier source="DE-28">{substring-after(substring(.,9), '/')}</mods:recordIdentifier>
+        <mods:recordIdentifier source="DE-28">{translate(substring-after(substring(.,9), '/'),'/','_')}</mods:recordIdentifier>
       </xsl:for-each>
       <xsl:for-each select="./p:datafield[@tag='004U']/p:subfield[@code='0' and contains(., 'gbv:519')]"> <!-- 4950 (kein eigenes Feld) -->
         <mods:recordIdentifier source="DE-519">dbhsnb/{substring(.,20,string-length(.)-19-2)}</mods:recordIdentifier>
diff --git a/pica2mods-xslt/src/test/resources/testFiles/default/1747633283.xml b/pica2mods-xslt/src/test/resources/testFiles/default/1747633283.xml
index c59a11ab..ce2b9f13 100644
--- a/pica2mods-xslt/src/test/resources/testFiles/default/1747633283.xml
+++ b/pica2mods-xslt/src/test/resources/testFiles/default/1747633283.xml
@@ -85,7 +85,7 @@
         <mods:edition>[Electronic edition]</mods:edition>
     </mods:originInfo>
     <mods:recordInfo>
-        <mods:recordIdentifier source="DE-28">rosdok/ppn1747633283</mods:recordIdentifier>
+        <mods:recordIdentifier source="DE-28">rosdok_ppn1747633283</mods:recordIdentifier>
         <mods:recordOrigin>Converted from PICA to MODS using Pica2Mods XSLT Transformator 2.0-SNAPSHOT [SCM: "master" "v1.3.1-46" "2021-02-26T20:53:04+0100"]</mods:recordOrigin>
     </mods:recordInfo>
     <mods:note type="source note">GutachterInnen: Prof. Dr. med. Timo Kirschstein (Oscar Langendorff Institut für Physiologie, Universitätsmedizin Rostock), Prof. Dr. med. Astrid Bertsche (Kinder- und Jugendklinik, Universitätsmedizin Rostock), Prof. Dr. med. Toni Schneider (Universitätsklinikum Köln, Institut für Neurophysiologie)</mods:note>
diff --git a/pica2mods-xslt/src/test/resources/testFiles/default/883825902.xml b/pica2mods-xslt/src/test/resources/testFiles/default/883825902.xml
index e96cf30d..6818c87f 100644
--- a/pica2mods-xslt/src/test/resources/testFiles/default/883825902.xml
+++ b/pica2mods-xslt/src/test/resources/testFiles/default/883825902.xml
@@ -85,7 +85,7 @@
         <mods:dateCaptured encoding="w3cdtf" keyDate="yes">2017</mods:dateCaptured>
     </mods:originInfo>
     <mods:recordInfo>
-        <mods:recordIdentifier source="DE-28">rosdok/ppn883825902</mods:recordIdentifier>
+        <mods:recordIdentifier source="DE-28">rosdok_ppn883825902</mods:recordIdentifier>
         <mods:descriptionStandard>rda</mods:descriptionStandard>
         <mods:recordOrigin>Converted from PICA to MODS using Pica2Mods XSLT Transformator 2.0-SNAPSHOT [SCM: "master" "v1.3.1-46" "2021-02-26T20:53:04+0100"]</mods:recordOrigin>
     </mods:recordInfo>