diff --git a/src/main/java/com/bc/zarr/ZarrHeader.java b/src/main/java/com/bc/zarr/ZarrHeader.java
index 80f708c..da6a891 100644
--- a/src/main/java/com/bc/zarr/ZarrHeader.java
+++ b/src/main/java/com/bc/zarr/ZarrHeader.java
@@ -149,10 +149,11 @@ public void serialize(ZarrHeader value, JsonGenerator gen, SerializerProvider pr
             gen.writeObjectField("order", value.order);
             gen.writeObjectField("shape", value.getShape());
             gen.writeNumberField("zarr_format", value.zarr_format);
-            if (value.nested != null) {
-                gen.writeBooleanField("nested", value.nested);
+            String dimensionSeparator = ".";
+            if (Boolean.TRUE.equals(value.nested)) {
+                dimensionSeparator = "/";
             }
-            gen.writeEndObject();
+            gen.writeStringField("dimension_separator", dimensionSeparator);
         }
     }
 
@@ -188,9 +189,22 @@ public ZarrHeader deserialize(JsonParser p, DeserializationContext ctxt) throws
             }
 
             Boolean nested = null;
-            JsonNode nestedNode = (JsonNode) root.path("nested");
-            if (!nestedNode.isMissingNode()) {
-                nested = nestedNode.asBoolean();
+            JsonNode dimensionSeparatorNode =
+                    (JsonNode) root.path("dimension_separator");
+            if (!dimensionSeparatorNode.isMissingNode()) {
+                String dimensionSeparator = dimensionSeparatorNode.asText();
+                switch (dimensionSeparator) {
+                    case ".":
+                        nested = false;
+                        break;
+                    case "/":
+                        nested = true;
+                        break;
+                    default:
+                        throw new IllegalArgumentException(
+                                "Unsupported dimension separator: "
+                                + dimensionSeparator);
+                }
             }
             return new ZarrHeader(shape, chunks, getRawDataType(dtype).toString(), getByteOrder(dtype), fill, compressor, nested);
         }
diff --git a/src/test/java/com/bc/zarr/ZarrUtilsTest.java b/src/test/java/com/bc/zarr/ZarrUtilsTest.java
index 22d2864..292ce30 100644
--- a/src/test/java/com/bc/zarr/ZarrUtilsTest.java
+++ b/src/test/java/com/bc/zarr/ZarrUtilsTest.java
@@ -184,7 +184,8 @@ private String expectedJson(boolean nullCompressor) {
         pw.println("        10,");
         pw.println("        15");
         pw.println("    ],");
-        pw.println("    \"zarr_format\": 2");
+        pw.println("    \"zarr_format\": 2,");
+        pw.println("    \"dimension_separator\": \".\"");
         pw.println("}");
 
         return strip(sw.toString());