Index: src/OFKernelEventObserver_select.m
==================================================================
--- src/OFKernelEventObserver_select.m
+++ src/OFKernelEventObserver_select.m
@@ -26,10 +26,12 @@
 #import "OFKernelEventObserver.h"
 #import "OFKernelEventObserver+Private.h"
 #import "OFKernelEventObserver_select.h"
 #import "OFArray.h"
 
+#import "OFOutOfRangeException.h"
+
 #import "socket_helpers.h"
 
 @implementation OFKernelEventObserver_select
 - init
 {
@@ -43,25 +45,37 @@
 	return self;
 }
 
 - (void)OF_addFileDescriptorForReading: (int)fd
 {
+	if (fd >= FD_SETSIZE)
+		@throw [OFOutOfRangeException exception];
+
 	FD_SET(fd, &_readFDs);
 }
 
 - (void)OF_addFileDescriptorForWriting: (int)fd
 {
+	if (fd >= FD_SETSIZE)
+		@throw [OFOutOfRangeException exception];
+
 	FD_SET(fd, &_writeFDs);
 }
 
 - (void)OF_removeFileDescriptorForReading: (int)fd
 {
+	if (fd >= FD_SETSIZE)
+		@throw [OFOutOfRangeException exception];
+
 	FD_CLR(fd, &_readFDs);
 }
 
 - (void)OF_removeFileDescriptorForWriting: (int)fd
 {
+	if (fd >= FD_SETSIZE)
+		@throw [OFOutOfRangeException exception];
+
 	FD_CLR(fd, &_writeFDs);
 }
 
 - (bool)observeForTimeInterval: (of_time_interval_t)timeInterval
 {