@@ -17,12 +17,13 @@
 #include "config.h"
 
 #define OF_STREAM_OBSERVER_M
 #define __NO_EXT_QNX
 
-#include <assert.h>
 #include <unistd.h>
+
+#include <assert.h>
 
 #import "OFStreamObserver.h"
 #import "OFArray.h"
 #import "OFDictionary.h"
 #import "OFStream.h"
@@ -44,10 +45,12 @@
 #endif
 
 #import "OFInitializationFailedException.h"
 #import "OFNotImplementedException.h"
 #import "OFOutOfRangeException.h"
+
+#import "macros.h"
 
 enum {
 	QUEUE_ADD = 0,
 	QUEUE_REMOVE = 1,
 	QUEUE_READ = 0,
@@ -194,13 +197,13 @@
 	} @finally {
 		[mutex unlock];
 	}
 
 #ifndef _WIN32
-	assert(write(cancelFD[1], "", 1) > 0);
+	OF_ENSURE(write(cancelFD[1], "", 1) > 0);
 #else
-	assert(sendto(cancelFD[1], "", 1, 0, (struct sockaddr*)&cancelAddr,
+	OF_ENSURE(sendto(cancelFD[1], "", 1, 0, (struct sockaddr*)&cancelAddr,
 	    sizeof(cancelAddr)) > 0);
 #endif
 }
 
 - (void)addStreamForWriting: (OFStream*)stream
@@ -216,13 +219,13 @@
 	} @finally {
 		[mutex unlock];
 	}
 
 #ifndef _WIN32
-	assert(write(cancelFD[1], "", 1) > 0);
+	OF_ENSURE(write(cancelFD[1], "", 1) > 0);
 #else
-	assert(sendto(cancelFD[1], "", 1, 0, (struct sockaddr*)&cancelAddr,
+	OF_ENSURE(sendto(cancelFD[1], "", 1, 0, (struct sockaddr*)&cancelAddr,
 	    sizeof(cancelAddr)) > 0);
 #endif
 }
 
 - (void)removeStreamForReading: (OFStream*)stream
@@ -238,13 +241,13 @@
 	} @finally {
 		[mutex unlock];
 	}
 
 #ifndef _WIN32
-	assert(write(cancelFD[1], "", 1) > 0);
+	OF_ENSURE(write(cancelFD[1], "", 1) > 0);
 #else
-	assert(sendto(cancelFD[1], "", 1, 0, (struct sockaddr*)&cancelAddr,
+	OF_ENSURE(sendto(cancelFD[1], "", 1, 0, (struct sockaddr*)&cancelAddr,
 	    sizeof(cancelAddr)) > 0);
 #endif
 }
 
 - (void)removeStreamForWriting: (OFStream*)stream
@@ -260,13 +263,13 @@
 	} @finally {
 		[mutex unlock];
 	}
 
 #ifndef _WIN32
-	assert(write(cancelFD[1], "", 1) > 0);
+	OF_ENSURE(write(cancelFD[1], "", 1) > 0);
 #else
-	assert(sendto(cancelFD[1], "", 1, 0, (struct sockaddr*)&cancelAddr,
+	OF_ENSURE(sendto(cancelFD[1], "", 1, 0, (struct sockaddr*)&cancelAddr,
 	    sizeof(cancelAddr)) > 0);
 #endif
 }
 
 - (void)_addFileDescriptorForReading: (int)fd