diff --git a/src/main/java/ee/ut/dendroloj/Dendrologist.java b/src/main/java/ee/ut/dendroloj/Dendrologist.java
index 8917986..4a2c54d 100644
--- a/src/main/java/ee/ut/dendroloj/Dendrologist.java
+++ b/src/main/java/ee/ut/dendroloj/Dendrologist.java
@@ -25,6 +25,9 @@ private Dendrologist() {
      * Default: {@code 1.0}
      */
     public static void setUIScale(double uiScale) {
+        if (awake) {
+            throw new IllegalStateException("Cannot set UI scale after dendrologist has woken up");
+        }
         Dendrologist.uiScale = uiScale;
     }