diff --git a/src/observer.ts b/src/observer.ts
index f926e742..b2fa63c7 100644
--- a/src/observer.ts
+++ b/src/observer.ts
@@ -78,6 +78,9 @@ export function createObserver(
 }
 
 export function observeElement(element: Instance) {
+  if (element.observer && !observerElementsMap.has(element.observer)) {
+    observerElementsMap.set(element.observer, new Set<Instance>());
+  }
   observerElementsMap.get(element.observer)?.add(element);
   element.observer!.observe(element.target!);
 }
diff --git a/test/unit/observer.spec.js b/test/unit/observer.spec.js
index 5b8d33cc..0c527bc2 100644
--- a/test/unit/observer.spec.js
+++ b/test/unit/observer.spec.js
@@ -194,4 +194,20 @@ describe('findObserverElement', () => {
         expect(instance1).toEqual(entry1);
         expect(instance2).toEqual(entry2);
     });
+
+    test('two subsequent createObserver calls should not produce two observers', () => {
+        const observer1 = createObserver();
+        const observer2 = createObserver();
+        expect(observer1).toEqual(observer2);
+    });
+
+    test('observing element should add target to observerElementsMap even if there is no such observer key', () => {
+        const observer = createObserver();
+        const entry = { observer, target: target1 };
+        observeElement(entry);
+        unobserveElement(entry, entry.target);
+        observeElement(entry);
+        const instance = findObserverElement(observer, entry);
+        expect(instance).toEqual(entry);
+    });
 });