Index: src/OFPollKernelEventObserver.m
==================================================================
--- src/OFPollKernelEventObserver.m
+++ src/OFPollKernelEventObserver.m
@@ -71,13 +71,21 @@
 
 - (void)of_addObject: (id)object
       fileDescriptor: (int)fd
 	      events: (short)events
 {
-	struct pollfd *FDs = _FDs.mutableItems;
-	size_t count = _FDs.count;
-	bool found = false;
+	struct pollfd *FDs;
+	size_t count;
+	bool found;
+
+	if (fd < 0)
+		@throw [OFObserveFailedException exceptionWithObserver: self
+								 errNo: EBADF];
+
+	FDs = _FDs.mutableItems;
+	count = _FDs.count;
+	found = false;
 
 	for (size_t i = 0; i < count; i++) {
 		if (FDs[i].fd == fd) {
 			FDs[i].events |= events;
 			found = true;
@@ -102,12 +110,19 @@
 
 - (void)of_removeObject: (id)object
 	 fileDescriptor: (int)fd
 		 events: (short)events
 {
-	struct pollfd *FDs = _FDs.mutableItems;
-	size_t nFDs = _FDs.count;
+	struct pollfd *FDs;
+	size_t nFDs;
+
+	if (fd < 0)
+		@throw [OFObserveFailedException exceptionWithObserver: self
+								 errNo: EBADF];
+
+	FDs = _FDs.mutableItems;
+	nFDs = _FDs.count;
 
 	for (size_t i = 0; i < nFDs; i++) {
 		if (FDs[i].fd == fd) {
 			FDs[i].events &= ~events;
 

Index: src/OFSelectKernelEventObserver.m
==================================================================
--- src/OFSelectKernelEventObserver.m
+++ src/OFSelectKernelEventObserver.m
@@ -47,37 +47,46 @@
 @implementation OFSelectKernelEventObserver
 - (instancetype)init
 {
 	self = [super init];
 
+	@try {
 #ifdef OF_AMIGAOS
-	_maxFD = 0;
+		_maxFD = 0;
 #else
 # ifndef OF_WINDOWS
-	if (_cancelFD[0] >= (int)FD_SETSIZE)
-		@throw [OFInitializationFailedException
-		    exceptionWithClass: self.class];
+		if (_cancelFD[0] >= (int)FD_SETSIZE)
+			@throw [OFInitializationFailedException
+			    exceptionWithClass: self.class];
 # endif
 
-	FD_ZERO(&_readFDs);
-	FD_ZERO(&_writeFDs);
-	FD_SET(_cancelFD[0], &_readFDs);
-
-	if (_cancelFD[0] > INT_MAX)
-		@throw [OFOutOfRangeException exception];
-
-	_maxFD = (int)_cancelFD[0];
+		FD_ZERO(&_readFDs);
+		FD_ZERO(&_writeFDs);
+		FD_SET(_cancelFD[0], &_readFDs);
+
+		if (_cancelFD[0] > INT_MAX)
+			@throw [OFOutOfRangeException exception];
+
+		_maxFD = (int)_cancelFD[0];
 #endif
+	} @catch (id e) {
+		[self release];
+		@throw e;
+	}
 
 	return self;
 }
 
 - (void)addObjectForReading: (id <OFReadyForReadingObserving>)object
 {
 	int fd = object.fileDescriptorForReading;
 
-	if (fd < 0 || fd > INT_MAX - 1)
+	if (fd < 0)
+		@throw [OFObserveFailedException exceptionWithObserver: self
+								 errNo: EBADF];
+
+	if (fd > INT_MAX - 1)
 		@throw [OFOutOfRangeException exception];
 
 #ifndef OF_WINDOWS
 	if (fd >= (int)FD_SETSIZE)
 		@throw [OFOutOfRangeException exception];
@@ -93,11 +102,15 @@
 
 - (void)addObjectForWriting: (id <OFReadyForWritingObserving>)object
 {
 	int fd = object.fileDescriptorForWriting;
 
-	if (fd < 0 || fd > INT_MAX - 1)
+	if (fd < 0)
+		@throw [OFObserveFailedException exceptionWithObserver: self
+								 errNo: EBADF];
+
+	if (fd > INT_MAX - 1)
 		@throw [OFOutOfRangeException exception];
 
 #ifndef OF_WINDOWS
 	if (fd >= (int)FD_SETSIZE)
 		@throw [OFOutOfRangeException exception];
@@ -116,11 +129,12 @@
 	/* TODO: Adjust _maxFD */
 
 	int fd = object.fileDescriptorForReading;
 
 	if (fd < 0)
-		@throw [OFOutOfRangeException exception];
+		@throw [OFObserveFailedException exceptionWithObserver: self
+								 errNo: EBADF];
 
 #ifndef OF_WINDOWS
 	if (fd >= (int)FD_SETSIZE)
 		@throw [OFOutOfRangeException exception];
 #endif
@@ -135,11 +149,13 @@
 	/* TODO: Adjust _maxFD */
 
 	int fd = object.fileDescriptorForWriting;
 
 	if (fd < 0)
-		@throw [OFOutOfRangeException exception];
+		@throw [OFObserveFailedException exceptionWithObserver: self
+								 errNo: EBADF];
+
 
 #ifndef OF_WINDOWS
 	if (fd >= (int)FD_SETSIZE)
 		@throw [OFOutOfRangeException exception];
 #endif