diff --git a/cdm/s3/src/main/java/thredds/inventory/s3/MFileS3.java b/cdm/s3/src/main/java/thredds/inventory/s3/MFileS3.java
index d6f5e6ba07..8d9ab9bd08 100644
--- a/cdm/s3/src/main/java/thredds/inventory/s3/MFileS3.java
+++ b/cdm/s3/src/main/java/thredds/inventory/s3/MFileS3.java
@@ -399,10 +399,9 @@ public String relativize(MFile other) {
 
     if (getDelimiter() != null && getDelimiter().equals("/") && getDelimiter().equals(otherS3.getDelimiter())
         && cdmS3Uri.getBucket().equals(otherS3.cdmS3Uri.getBucket())) {
-      final String key = getKey();
-      final String otherKey = otherS3.getKey();
-      return key == null || otherKey == null ? ""
-          : Paths.get("/" + key).relativize(Paths.get("/" + otherKey)).toString();
+      final String key = getKey() == null ? "/" : "/" + getKey();
+      final String otherKey = otherS3.getKey() == null ? "/" : "/" + otherS3.getKey();
+      return Paths.get(key).relativize(Paths.get(otherKey)).toString();
     }
 
     return "";
diff --git a/cdm/s3/src/test/java/thredds/inventory/s3/TestMFileS3.java b/cdm/s3/src/test/java/thredds/inventory/s3/TestMFileS3.java
index 6334bdde53..6c7a2b1c07 100644
--- a/cdm/s3/src/test/java/thredds/inventory/s3/TestMFileS3.java
+++ b/cdm/s3/src/test/java/thredds/inventory/s3/TestMFileS3.java
@@ -525,6 +525,9 @@ public static List<Object[]> getTestParameters() {
           {"cdms3:bucket?a/long/#delimiter=/", "cdms3:bucket?a/long/key", ""},
           {"cdms3:bucket", "cdms3:bucket?a/long/key", ""}, {"cdms3:bucket?a/long/key", "cdms3:bucket", ""},
 
+          {"cdms3:bucket#delimiter=/", "cdms3:bucket?/#delimiter=/", ""},
+          {"cdms3:bucket#delimiter=/", "cdms3:bucket?key/#delimiter=/", "key"},
+          {"cdms3:bucket?key#delimiter=/", "cdms3:bucket?#delimiter=/", ".."},
           {"cdms3:bucket?a/long/#delimiter=/", "cdms3:bucket?a/long/key/#delimiter=/", "key"},
           {"cdms3:bucket?a/long/#delimiter=/", "cdms3:bucket?a/long/key#delimiter=/", "key"},
           {"cdms3:bucket?a/long#delimiter=/", "cdms3:bucket?a/long/key/#delimiter=/", "key"},