Index: src/OFRunLoop.h
==================================================================
--- src/OFRunLoop.h
+++ src/OFRunLoop.h
@@ -88,11 +88,13 @@
  * @brief Adds an OFTimer to the run loop.
  *
  * @param timer The timer to add
  */
 - (void)addTimer: (OFTimer*)timer;
+
+- (void)OF_removeTimer: (OFTimer*)timer;
 
 /*!
  * @brief Starts the run loop.
  */
 - (void)run;
 @end

Index: src/OFRunLoop.m
==================================================================
--- src/OFRunLoop.m
+++ src/OFRunLoop.m
@@ -316,12 +316,32 @@
 		[timersQueue insertObject: timer];
 	} @finally {
 		[timersQueueLock unlock];
 	}
 
+	[timer OF_setInRunLoop: self];
+
 	[streamObserver cancel];
 }
+
+- (void)OF_removeTimer: (OFTimer*)timer
+{
+	[timersQueueLock lock];
+	@try {
+		of_list_object_t *iter;
+
+		for (iter = [timersQueue firstListObject]; iter != NULL;
+		    iter = iter->next) {
+			if ([iter->object isEqual: timer]) {
+				[timersQueue removeListObject: iter];
+				break;
+			}
+		}
+	} @finally {
+		[timersQueueLock unlock];
+	}
+}
 
 - (void)streamIsReadyForReading: (OFStream*)stream
 {
 	OFList *queue = [readQueues objectForKey: stream];
 	of_list_object_t *listObject;
@@ -565,10 +585,12 @@
 			    OF_ORDERED_DESCENDING) {
 				timer =
 				    [[listObject->object retain] autorelease];
 
 				[timersQueue removeListObject: listObject];
+
+				[timer OF_setInRunLoop: nil];
 			} else
 				timer = nil;
 		} @finally {
 			[timersQueueLock unlock];
 		}

Index: src/OFTimer.h
==================================================================
--- src/OFTimer.h
+++ src/OFTimer.h
@@ -17,10 +17,11 @@
 #import "OFObject.h"
 
 @class OFTimer;
 @class OFDate;
 @class OFCondition;
+@class OFRunLoop;
 
 #ifdef OF_HAVE_BLOCKS
 typedef void (^of_timer_block_t)(OFTimer*);
 #endif
 
@@ -38,14 +39,15 @@
 #ifdef OF_HAVE_BLOCKS
 	of_timer_block_t block;
 #endif
 	BOOL isValid, done;
 	OFCondition *condition;
+	OFRunLoop *inRunLoop;
 }
 
 #ifdef OF_HAVE_PROPERTIES
-@property (readonly, retain) OFDate *fireDate;
+@property (retain) OFDate *fireDate;
 #endif
 
 /*!
  * @brief Creates and schedules a new timer with the specified time interval.
  *
@@ -273,10 +275,22 @@
  *
  * @return The next date at which the timer will fire
  */
 - (OFDate*)fireDate;
 
+/*!
+ * @brief Sets the next date at which the timer will fire.
+ *
+ * If the timer is already scheduled in a run loop, it will be rescheduled.
+ * Note that rescheduling is an expensive operation, though it still might be
+ * preferrable to reschedule instead of invalidating the timer and creating a
+ * new one.
+ *
+ * @param fireDate The next date at which the timer will fire
+ */
+- (void)setFireDate: (OFDate*)fireDate;
+
 /*!
  * @brief Invalidates the timer, preventing it from firing.
  */
 - (void)invalidate;
 
@@ -298,6 +312,8 @@
 
 /*!
  * @brief Waits until the timer fired.
  */
 - (void)waitUntilDone;
+
+- (void)OF_setInRunLoop: (OFRunLoop*)inRunLoop;
 @end

Index: src/OFTimer.m
==================================================================
--- src/OFTimer.m
+++ src/OFTimer.m
@@ -14,10 +14,12 @@
  * file.
  */
 
 #include "config.h"
 
+#include <assert.h>
+
 #import "OFTimer.h"
 #import "OFDate.h"
 #import "OFRunLoop.h"
 #import "OFCondition.h"
 
@@ -313,10 +315,16 @@
 }
 #endif
 
 - (void)dealloc
 {
+	/*
+	 * The run loop references the timer, so it should never be deallocated
+	 * if it is still in a run loop.
+	 */
+	assert(inRunLoop == nil);
+
 	[fireDate release];
 	[target release];
 	[object1 release];
 	[object2 release];
 #ifdef OF_HAVE_BLOCKS
@@ -389,10 +397,26 @@
 
 - (OFDate*)fireDate
 {
 	OF_GETTER(fireDate, YES)
 }
+
+- (void)setFireDate: (OFDate*)fireDate_
+{
+	[self retain];
+	@try {
+		@synchronized (self) {
+			[inRunLoop OF_removeTimer: self];
+
+			OF_SETTER(fireDate, fireDate_, YES, 0)
+
+			[inRunLoop addTimer: self];
+		}
+	} @finally {
+		[self release];
+	}
+}
 
 - (double)timeInterval
 {
 	return interval;
 }
@@ -419,6 +443,11 @@
 		[condition wait];
 	} @finally {
 		[condition unlock];
 	}
 }
+
+- (void)OF_setInRunLoop: (OFRunLoop*)inRunLoop_
+{
+	OF_SETTER(inRunLoop, inRunLoop_, YES, 0)
+}
 @end