Index: src/OFStream.h
==================================================================
--- src/OFStream.h
+++ src/OFStream.h
@@ -59,12 +59,11 @@
 {
 	char   *cache;
 	char   *writeBuffer;
 	size_t cacheLength, writeBufferLength;
 	BOOL   writeBufferEnabled;
-	BOOL   blocking;
-	BOOL   waitingForDelimiter;
+	BOOL   blocking, waitingForDelimiter;
 }
 
 #ifdef OF_HAVE_PROPERTIES
 @property (getter=isWriteBufferEnabled) BOOL writeBufferEnabled;
 @property (getter=isBlocking) BOOL blocking;

Index: src/OFStream.m
==================================================================
--- src/OFStream.m
+++ src/OFStream.m
@@ -37,10 +37,11 @@
 #import "OFSystemInfo.h"
 #import "OFRunLoop.h"
 
 #import "OFInvalidArgumentException.h"
 #import "OFInvalidFormatException.h"
+#import "OFNotImplementedException.h"
 #import "OFSetOptionFailedException.h"
 
 #import "macros.h"
 #import "of_asprintf.h"
 
@@ -99,20 +100,20 @@
 	return [self retain];
 }
 
 - (BOOL)isAtEndOfStream
 {
-	if (cache != NULL)
+	if (cacheLength > 0)
 		return NO;
 
 	return [self lowlevelIsAtEndOfStream];
 }
 
 - (size_t)readIntoBuffer: (void*)buffer
 		  length: (size_t)length
 {
-	if (cache == NULL)
+	if (cacheLength == 0)
 		return [self lowlevelReadIntoBuffer: buffer
 					     length: length];
 
 	if (length >= cacheLength) {
 		size_t ret = cacheLength;
@@ -1464,33 +1465,66 @@
 }
 
 - (void)setBlocking: (BOOL)enable
 {
 #ifndef _WIN32
-	int readFlags, writeFlags;
-
-	readFlags = fcntl([self fileDescriptorForReading], F_GETFL);
-	writeFlags = fcntl([self fileDescriptorForWriting], F_GETFL);
-
-	if (readFlags == -1 || writeFlags == -1)
-		@throw [OFSetOptionFailedException
-		    exceptionWithClass: [self class]
-				stream: self];
-
-	if (enable) {
-		readFlags &= ~O_NONBLOCK;
-		writeFlags &= ~O_NONBLOCK;
-	} else {
-		readFlags |= O_NONBLOCK;
-		writeFlags |= O_NONBLOCK;
-	}
-
-	if (fcntl([self fileDescriptorForReading], F_SETFL, readFlags) == -1 ||
-	    fcntl([self fileDescriptorForWriting], F_SETFL, writeFlags) == -1)
-		@throw [OFSetOptionFailedException
-		    exceptionWithClass: [self class]
-				stream: self];
+	BOOL readImplemented = NO, writeImplemented = NO;
+
+	@try {
+		int readFlags;
+
+		readFlags = fcntl([self fileDescriptorForReading], F_GETFL);
+
+		readImplemented = YES;
+
+		if (readFlags == -1)
+			@throw [OFSetOptionFailedException
+			    exceptionWithClass: [self class]
+					stream: self];
+
+		if (enable)
+			readFlags &= ~O_NONBLOCK;
+		else
+			readFlags |= O_NONBLOCK;
+
+		if (fcntl([self fileDescriptorForReading], F_SETFL,
+		    readFlags) == -1)
+			@throw [OFSetOptionFailedException
+			    exceptionWithClass: [self class]
+					stream: self];
+	} @catch (OFNotImplementedException *e) {
+	}
+
+	@try {
+		int writeFlags;
+
+		writeFlags = fcntl([self fileDescriptorForWriting], F_GETFL);
+
+		writeImplemented = YES;
+
+		if (writeFlags == -1)
+			@throw [OFSetOptionFailedException
+			    exceptionWithClass: [self class]
+					stream: self];
+
+		if (enable)
+			writeFlags &= ~O_NONBLOCK;
+		else
+			writeFlags |= O_NONBLOCK;
+
+		if (fcntl([self fileDescriptorForWriting], F_SETFL,
+		    writeFlags) == -1)
+			@throw [OFSetOptionFailedException
+			    exceptionWithClass: [self class]
+					stream: self];
+	} @catch (OFNotImplementedException *e) {
+	}
+
+	if (!readImplemented && !writeImplemented)
+		@throw [OFNotImplementedException
+		    exceptionWithClass: [self class]
+			      selector: _cmd];
 #else
 	[self doesNotRecognizeSelector: _cmd];
 	abort();
 #endif
 }