Index: src/OFSeekableStream.m
==================================================================
--- src/OFSeekableStream.m
+++ src/OFSeekableStream.m
@@ -31,10 +31,11 @@
 					      selector: _cmd];
 }
 
 - seekToOffset: (off_t)offset
 {
+	[self flushWriteCache];
 	[self _seekToOffset: offset];
 
 	[self freeMemory: cache];
 	cache = NULL;
 	cache_len = 0;
@@ -44,10 +45,11 @@
 
 - (off_t)seekForwardWithOffset: (off_t)offset
 {
 	off_t ret;
 
+	[self flushWriteCache];
 	ret = [self _seekForwardWithOffset: offset - cache_len];
 
 	[self freeMemory: cache];
 	cache = NULL;
 	cache_len = 0;
@@ -55,14 +57,17 @@
 	return ret;
 }
 
 - (off_t)seekToOffsetRelativeToEnd: (off_t)offset
 {
-	off_t ret = [self _seekToOffsetRelativeToEnd: offset];
+	off_t ret;
+
+	[self flushWriteCache];
+	ret = [self _seekToOffsetRelativeToEnd: offset];
 
 	[self freeMemory: cache];
 	cache = NULL;
 	cache_len = 0;
 
 	return ret;
 }
 @end

Index: src/OFStream.m
==================================================================
--- src/OFStream.m
+++ src/OFStream.m
@@ -504,10 +504,13 @@
 	return self;
 }
 
 - flushWriteCache
 {
+	if (wcache == NULL)
+		return self;
+
 	[self _writeNBytes: wcache_len
 		fromBuffer: wcache];
 
 	[self freeMemory: wcache];
 	wcache = NULL;