diff --git a/src/run.rs b/src/run.rs
index 6fcfb2e..bf5ba8d 100644
--- a/src/run.rs
+++ b/src/run.rs
@@ -79,15 +79,22 @@ impl Run{
 		}
 	}
 	pub fn finish(&mut self,time:Time)->Result<(),Error>{
-		match &self.state{
-			RunState::Created=>Err(Error::NotStarted),
-			RunState::Started{timer}=>{
-				self.state=RunState::Finished{
-					timer:TimerFixed::<Realtime,Paused>::new(time,timer.time(time)),
-				};
-				Ok(())
-			},
-			RunState::Finished{..}=>Err(Error::AlreadyFinished),
+		//code based on std::mem::replace
+		let dest=&mut self.state;
+		//let's ignore ownership rules for a moment
+		unsafe{
+			let state=std::ptr::read(dest);
+			match state{
+				RunState::Created=>Err(Error::NotStarted),
+				RunState::Started{timer}=>{
+					let src=RunState::Finished{
+						timer:timer.pause(time),
+					};
+					std::ptr::write(dest,src);
+					Ok(())
+				},
+				RunState::Finished{..}=>Err(Error::AlreadyFinished),
+			}
 		}
 	}
 	pub fn flag(&mut self,flag_reason:FlagReason){