diff --git a/escher/include/escher/responder.h b/escher/include/escher/responder.h
index c8315c5bb..b0918b5fc 100644
--- a/escher/include/escher/responder.h
+++ b/escher/include/escher/responder.h
@@ -15,6 +15,7 @@ public:
   Responder * commonAncestorWith(Responder * responder);
   void setParentResponder(Responder * responder) { m_parentResponder = responder; }
 private:
+  bool hasAncestor(Responder * responder) const;
   Responder * m_parentResponder;
 };
 
diff --git a/escher/src/responder.cpp b/escher/src/responder.cpp
index ba0a120f4..72f12c85e 100644
--- a/escher/src/responder.cpp
+++ b/escher/src/responder.cpp
@@ -7,33 +7,24 @@ Responder * Responder::commonAncestorWith(Responder * responder) {
   if (responder == nullptr) {
     return nullptr;
   }
-  if (this == responder) {
-    return this;
+  Responder * p = this;
+  while (p != nullptr) {
+    if (responder->hasAncestor(p)) {
+      return p;
+    }
+    p = p->parentResponder();
   }
-  Responder * rootResponder = this;
-  while (rootResponder->parentResponder() != responder && rootResponder->parentResponder() != nullptr) {
-    rootResponder = rootResponder->parentResponder();
-  }
-  if (rootResponder->parentResponder() == responder) {
-    return responder;
-  }
-  rootResponder = responder;
-  while (rootResponder->parentResponder() != this && rootResponder->parentResponder() != nullptr) {
-    rootResponder = rootResponder->parentResponder();
-  }
-  if (rootResponder->parentResponder() == this) {
-    return this;
-  }
-  Responder * r = nullptr;
-  if (parentResponder()) {
-    r = parentResponder()->commonAncestorWith(responder);
-   }
-   Responder * s = nullptr;
-   if (responder->parentResponder()) {
-    s = commonAncestorWith(responder->parentResponder());
-   }
-   if (r) {
-    return r;
-  }
-  return s;
+  return nullptr;
+}
+
+bool Responder::hasAncestor(Responder * responder) const {
+  assert(responder != nullptr);
+  Responder * p = const_cast<Responder *>(this);
+  while (p != nullptr) {
+    if (p == responder) {
+      return true;
+    }
+    p = p->parentResponder();
+  }
+  return false;
 }