diff --git a/webcommon/javascript2.editor/src/org/netbeans/modules/javascript2/editor/navigation/JsonOccurrencesFinder.java b/webcommon/javascript2.editor/src/org/netbeans/modules/javascript2/editor/navigation/JsonOccurrencesFinder.java
index b8f7e666e544..56150ac66e5e 100644
--- a/webcommon/javascript2.editor/src/org/netbeans/modules/javascript2/editor/navigation/JsonOccurrencesFinder.java
+++ b/webcommon/javascript2.editor/src/org/netbeans/modules/javascript2/editor/navigation/JsonOccurrencesFinder.java
@@ -59,7 +59,9 @@ public void setCaretPosition(int position) {
 
     @Override
     public Map<OffsetRange, ColoringAttributes> getOccurrences() {
-        return range2Attribs;
+        return range2Attribs != null
+                ? Collections.unmodifiableMap(range2Attribs)
+                : Collections.emptyMap();
     }
 
     @Override
diff --git a/webcommon/javascript2.editor/src/org/netbeans/modules/javascript2/editor/navigation/OccurrencesFinderImpl.java b/webcommon/javascript2.editor/src/org/netbeans/modules/javascript2/editor/navigation/OccurrencesFinderImpl.java
index b26a6a3b6c45..512db9486ea3 100644
--- a/webcommon/javascript2.editor/src/org/netbeans/modules/javascript2/editor/navigation/OccurrencesFinderImpl.java
+++ b/webcommon/javascript2.editor/src/org/netbeans/modules/javascript2/editor/navigation/OccurrencesFinderImpl.java
@@ -59,7 +59,9 @@ public void setCaretPosition(int position) {
 
     @Override
     public Map<OffsetRange, ColoringAttributes> getOccurrences() {
-        return range2Attribs;
+        return range2Attribs != null
+                ? Collections.unmodifiableMap(range2Attribs)
+                : Collections.emptyMap();
     }
 
     @Override