diff --git a/lib/icingadb/icingadb-objects.cpp b/lib/icingadb/icingadb-objects.cpp
index e98713e8c..7d63bcc56 100644
--- a/lib/icingadb/icingadb-objects.cpp
+++ b/lib/icingadb/icingadb-objects.cpp
@@ -1616,7 +1616,7 @@ Dictionary::Ptr IcingaDB::SerializeState(const Checkable::Ptr& checkable)
 
 		if (!cr->GetCommand().IsEmpty())
 			attrs->Set("commandline", FormatCommandLine(cr->GetCommand()));
-		attrs->Set("execution_time", TimestampToMilliseconds(cr->CalculateExecutionTime()));
+		attrs->Set("execution_time", TimestampToMilliseconds(fmax(0.0, cr->CalculateExecutionTime())));
 		attrs->Set("latency", TimestampToMilliseconds(cr->CalculateLatency()));
 		attrs->Set("check_source", cr->GetCheckSource());
 	}