diff --git a/lib/icinga/checkable-check.cpp b/lib/icinga/checkable-check.cpp
index 619e3c0ee..faf50694a 100644
--- a/lib/icinga/checkable-check.cpp
+++ b/lib/icinga/checkable-check.cpp
@@ -438,6 +438,12 @@ void Checkable::ExecuteCheck()
 	double scheduled_start = GetNextCheck();
 	double before_check = Utility::GetTime();
 
+	/* This calls SetNextCheck() which updates the CheckerComponent's idle/pending
+	 * queues and ensures that checks are not fired multiple times. ProcessCheckResult()
+	 * is called too late. See #6421.
+	 */
+	UpdateNextCheck();
+
 	bool reachable = IsReachable();
 
 	{