diff --git a/Audio/Chain/InputNode.m b/Audio/Chain/InputNode.m
index 021a90ea5..ae0d81bfb 100644
--- a/Audio/Chain/InputNode.m
+++ b/Audio/Chain/InputNode.m
@@ -33,6 +33,8 @@ static void *kInputNodeContext = &kInputNodeContext;
 }
 
 - (BOOL)openWithSource:(id<CogSource>)source {
+	[self removeObservers];
+
 	decoder = [AudioDecoder audioDecoderForSource:source];
 
 	if(decoder == nil)
@@ -63,6 +65,8 @@ static void *kInputNodeContext = &kInputNodeContext;
 }
 
 - (BOOL)openWithDecoder:(id<CogDecoder>)d {
+	[self removeObservers];
+
 	DLog(@"Opening with old decoder: %@", d);
 	decoder = d;
 
diff --git a/Audio/CogPluginMulti.h b/Audio/CogPluginMulti.h
index 6eac16c7e..0fed368e4 100644
--- a/Audio/CogPluginMulti.h
+++ b/Audio/CogPluginMulti.h
@@ -12,6 +12,7 @@
 @interface CogDecoderMulti : NSObject <CogDecoder> {
 	NSArray *theDecoders;
 	id<CogDecoder> theDecoder;
+	BOOL observersAdded;
 }
 
 - (id)initWithDecoders:(NSArray *)decoders;
diff --git a/Audio/CogPluginMulti.m b/Audio/CogPluginMulti.m
index 879705223..54834a0c3 100644
--- a/Audio/CogPluginMulti.m
+++ b/Audio/CogPluginMulti.m
@@ -113,20 +113,26 @@ static void *kCogDecoderMultiContext = &kCogDecoderMultiContext;
 }
 
 - (void)registerObservers {
-	[theDecoder addObserver:self
-	             forKeyPath:@"properties"
-	                options:(NSKeyValueObservingOptionNew)
-	                context:kCogDecoderMultiContext];
+	if(!observersAdded) {
+		[theDecoder addObserver:self
+		             forKeyPath:@"properties"
+		                options:(NSKeyValueObservingOptionNew)
+		                context:kCogDecoderMultiContext];
 
-	[theDecoder addObserver:self
-	             forKeyPath:@"metadata"
-	                options:(NSKeyValueObservingOptionNew)
-	                context:kCogDecoderMultiContext];
+		[theDecoder addObserver:self
+		             forKeyPath:@"metadata"
+		                options:(NSKeyValueObservingOptionNew)
+		                context:kCogDecoderMultiContext];
+		observersAdded = YES;
+	}
 }
 
 - (void)removeObservers {
-	[theDecoder removeObserver:self forKeyPath:@"properties" context:kCogDecoderMultiContext];
-	[theDecoder removeObserver:self forKeyPath:@"metadata" context:kCogDecoderMultiContext];
+	if(observersAdded) {
+		observersAdded = NO;
+		[theDecoder removeObserver:self forKeyPath:@"properties" context:kCogDecoderMultiContext];
+		[theDecoder removeObserver:self forKeyPath:@"metadata" context:kCogDecoderMultiContext];
+	}
 }
 
 - (BOOL)setTrack:(NSURL *)track {