diff --git a/brachytherapy.csl b/brachytherapy.csl
index cc827e885da..bfef7219202 100644
--- a/brachytherapy.csl
+++ b/brachytherapy.csl
@@ -38,7 +38,7 @@
   <macro name="access">
     <choose>
       <if variable="DOI">
-        <text variable="DOI" prefix="https://doi.org"/>
+        <text variable="DOI" prefix="https://doi.org/"/>
       </if>
       <else-if type="webpage post-weblog" match="any">
         <group delimiter=". ">
diff --git a/unified-style-sheet-for-linguistics.csl b/unified-style-sheet-for-linguistics.csl
index 62da0287d01..d5e5b544377 100644
--- a/unified-style-sheet-for-linguistics.csl
+++ b/unified-style-sheet-for-linguistics.csl
@@ -163,7 +163,7 @@
           <text macro="archive"/>
         </else-if>
       </choose>
-      <text variable="DOI" prefix="https://doi.org"/>
+      <text variable="DOI" prefix="https://doi.org/"/>
       <text variable="URL"/>
     </group>
     <group prefix=" (" suffix=")">