Index: src/OFObject.m
==================================================================
--- src/OFObject.m
+++ src/OFObject.m
@@ -607,21 +607,21 @@
 
 	objc_autoreleasePoolPop(pool);
 }
 
 - (void)performSelector: (SEL)selector
-	     withObject: (id)object
-	     withObject: (id)otherObject
+	     withObject: (id)object1
+	     withObject: (id)object2
 	     afterDelay: (double)delay
 {
 	void *pool = objc_autoreleasePoolPush();
 
 	[OFTimer scheduledTimerWithTimeInterval: delay
 					 target: self
 				       selector: selector
-					 object: object
-					 object: object
+					 object: object1
+					 object: object2
 					repeats: NO];
 
 	objc_autoreleasePoolPop(pool);
 }
 
@@ -655,21 +655,21 @@
 	objc_autoreleasePoolPop(pool);
 }
 
 - (void)performSelector: (SEL)selector
 	       onThread: (OFThread*)thread
-	     withObject: (id)object
-	     withObject: (id)otherObject
+	     withObject: (id)object1
+	     withObject: (id)object2
 	     afterDelay: (double)delay
 {
 	void *pool = objc_autoreleasePoolPush();
 
 	[[thread runLoop] addTimer: [OFTimer timerWithTimeInterval: delay
 							    target: self
 							  selector: selector
-							    object: object
-							    object: object
+							    object: object1
+							    object: object2
 							   repeats: NO]];
 
 	objc_autoreleasePoolPop(pool);
 }
 

Index: src/OFRunLoop.m
==================================================================
--- src/OFRunLoop.m
+++ src/OFRunLoop.m
@@ -320,11 +320,12 @@
 				[timersQueue removeListObject: listObject];
 			} else
 				timer = nil;
 		}
 
-		[timer fire];
+		if ([timer isValid])
+			[timer fire];
 
 		@synchronized (timersQueue) {
 			nextTimer = [[timersQueue firstObject] fireDate];
 		}
 

Index: src/OFTimer.h
==================================================================
--- src/OFTimer.h
+++ src/OFTimer.h
@@ -34,10 +34,11 @@
 	uint8_t arguments;
 	BOOL repeats;
 #ifdef OF_HAVE_BLOCKS
 	of_timer_block_t block;
 #endif
+	BOOL isValid;
 }
 
 /**
  * \brief Creates and schedules a new timer with the specified time interval.
  *
@@ -260,6 +261,27 @@
  * \brief Returns the next date at which the timer will fire.
  *
  * \return The next date at which the timer will fire
  */
 - (OFDate*)fireDate;
+
+/**
+ * \brief Invalidates the timer, preventing it from firing.
+ */
+- (void)invalidate;
+
+/**
+ * \brief Returns whether the timer is valid.
+ *
+ * \return Whether the timer is valid
+ */
+- (BOOL)isValid;
+
+/**
+ * \brief Returns the time interval in which the timer will repeat, if it is a
+ *	  repeating timer.
+ *
+ * \return The time interval in which the timer will repeat, if it is a
+ *	   repeating timer
+ */
+- (double)timeInterval;
 @end

Index: src/OFTimer.m
==================================================================
--- src/OFTimer.m
+++ src/OFTimer.m
@@ -216,10 +216,11 @@
 		selector = selector_;
 		object1 = [object1_ retain];
 		object2 = [object2_ retain];
 		arguments = arguments_;
 		repeats = repeats_;
+		isValid = YES;
 	} @catch (id e) {
 		[self release];
 		@throw e;
 	}
 
@@ -358,13 +359,29 @@
 		fireDate = [[OFDate alloc]
 		    initWithTimeIntervalSinceNow: interval];
 		[old release];
 
 		[[OFRunLoop currentRunLoop] addTimer: self];
-	}
+	} else
+		isValid = NO;
 }
 
 - (OFDate*)fireDate
 {
 	return [[fireDate retain] autorelease];
 }
+
+- (double)timeInterval
+{
+	return interval;
+}
+
+- (void)invalidate
+{
+	isValid = NO;
+}
+
+- (BOOL)isValid
+{
+	return isValid;
+}
 @end