diff --git a/rest-api/src/main/java/lcsb/mapviewer/api/projects/overlays/OverlayRestImpl.java b/rest-api/src/main/java/lcsb/mapviewer/api/projects/overlays/OverlayRestImpl.java
index 0ff7457c83efd5fcea8f1e4f334c1b010449e2e6..9bc0112531c8170259154bd1a4a22b9ab1f944e9 100644
--- a/rest-api/src/main/java/lcsb/mapviewer/api/projects/overlays/OverlayRestImpl.java
+++ b/rest-api/src/main/java/lcsb/mapviewer/api/projects/overlays/OverlayRestImpl.java
@@ -102,12 +102,13 @@ public class OverlayRestImpl extends BaseRestImpl {
     return result;
   }
 
-  private String getDeprecatedColumns(Layout overlay) {
+  private List<String> getDeprecatedColumns(Layout overlay) {
     try {
-      String result = "";
+      List<String> result = new ArrayList<>();
       for (ColorSchemaColumn column : new ColorSchemaReader().getDeprecatedColumns(overlay)) {
-        result += column.name() + ",";
+        result.add(column.name());
       }
+      logger.debug(result);
       return result;
     } catch (IOException | InvalidColorSchemaException e) {
       throw new InvalidStateException(e);
diff --git a/web/src/test/java/lcsb/mapviewer/web/OverlayControllerIntegrationTest.java b/web/src/test/java/lcsb/mapviewer/web/OverlayControllerIntegrationTest.java
index 705f1000d0bd74d40cf7e3bee4192097ceaf040f..5368aef970b0fad0e7eb22c766394e891b3ed355 100644
--- a/web/src/test/java/lcsb/mapviewer/web/OverlayControllerIntegrationTest.java
+++ b/web/src/test/java/lcsb/mapviewer/web/OverlayControllerIntegrationTest.java
@@ -1,6 +1,6 @@
 package lcsb.mapviewer.web;
 
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertEquals;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.*;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
@@ -1051,12 +1051,11 @@ public class OverlayControllerIntegrationTest extends ControllerIntegrationTest
     String response = mockMvc.perform(request)
         .andExpect(status().is2xxSuccessful())
         .andReturn().getResponse().getContentAsString();
-    String deprecatedColumns = new JsonParser()
+    int deprecatedColumns = new JsonParser()
         .parse(response)
-        .getAsJsonObject().get("deprecatedColumns").getAsString();
+        .getAsJsonObject().get("deprecatedColumns").getAsJsonArray().size();
 
-    assertNotNull(deprecatedColumns);
-    assertFalse(deprecatedColumns.isEmpty());
+    assertEquals(2, deprecatedColumns);
   }
 
 }