diff --git a/sortix/descriptor.cpp b/sortix/descriptor.cpp
index aac0a154..db916848 100644
--- a/sortix/descriptor.cpp
+++ b/sortix/descriptor.cpp
@@ -31,7 +31,6 @@
 #include <sortix/kernel/descriptor.h>
 #include <sortix/kernel/fsfunc.h>
 #include <sortix/kernel/string.h>
-#include <sortix/kernel/copy.h> // DEBUG
 #include <sortix/dirent.h>
 #include <sortix/fcntl.h>
 #include <sortix/seek.h>
@@ -50,7 +49,7 @@ const int ACCESS_FLAGS = O_READ | O_WRITE | O_EXEC | O_SEARCH;
 const int OPEN_FLAGS = O_CREAT | O_DIRECTORY | O_EXCL | O_TRUNC;
 
 // Flags that only make sense for descriptors.
-const int DESCRIPTOR_FLAGS = O_APPEND;
+const int DESCRIPTOR_FLAGS = O_APPEND | O_NONBLOCK;
 
 bool LinkInodeInDir(ioctx_t* ctx, Ref<Descriptor> dir, const char* name,
                     Ref<Inode> inode)
@@ -218,6 +217,7 @@ ssize_t Descriptor::read(ioctx_t* ctx, uint8_t* buf, size_t count)
 		return errno = EPERM, -1;
 	if ( !count ) { return 0; }
 	if ( (size_t) SSIZE_MAX < count ) { count = SSIZE_MAX; }
+	ctx->dflags = dflags;
 	if ( !IsSeekable() )
 		return vnode->read(ctx, buf, count);
 	// TODO: Locking here only allows one task to read/write at once.
@@ -235,6 +235,7 @@ ssize_t Descriptor::pread(ioctx_t* ctx, uint8_t* buf, size_t count, off_t off)
 	if ( off < 0 ) { errno = EINVAL; return -1; }
 	if ( !count ) { return 0; }
 	if ( SSIZE_MAX < count ) { count = SSIZE_MAX; }
+	ctx->dflags = dflags;
 	return vnode->pread(ctx, buf, count, off);
 }
 
@@ -244,6 +245,7 @@ ssize_t Descriptor::write(ioctx_t* ctx, const uint8_t* buf, size_t count)
 		return errno = EPERM, -1;
 	if ( !count ) { return 0; }
 	if ( SSIZE_MAX < count ) { count = SSIZE_MAX; }
+	ctx->dflags = dflags;
 	if ( !IsSeekable() )
 		return vnode->write(ctx, buf, count);
 	// TODO: Locking here only allows one task to read/write at once.
@@ -265,6 +267,7 @@ ssize_t Descriptor::pwrite(ioctx_t* ctx, const uint8_t* buf, size_t count, off_t
 	if ( off < 0 ) { errno = EINVAL; return -1; }
 	if ( !count ) { return 0; }
 	if ( SSIZE_MAX < count ) { count = SSIZE_MAX; }
+	ctx->dflags = dflags;
 	return vnode->pwrite(ctx, buf, count, off);
 }
 
diff --git a/sortix/include/sortix/fcntl.h b/sortix/include/sortix/fcntl.h
index 50b4722d..b28baa2c 100644
--- a/sortix/include/sortix/fcntl.h
+++ b/sortix/include/sortix/fcntl.h
@@ -22,8 +22,8 @@
 
 *******************************************************************************/
 
-#ifndef SORTIX_FCNTL_H
-#define SORTIX_FCNTL_H
+#ifndef INCLUDE_SORTIX_FCNTL_H
+#define INCLUDE_SORTIX_FCNTL_H
 
 #include <features.h>
 
@@ -42,6 +42,7 @@ __BEGIN_DECLS
 #define O_TRUNC (1<<8)
 #define O_CLOFORK (1<<9)
 #define O_SEARCH (1<<10)
+#define O_NONBLOCK (1<<11)
 // TODO: O_NOFOLLOW.
 
 #define FD_CLOEXEC (1<<0)
diff --git a/sortix/include/sortix/kernel/ioctx.h b/sortix/include/sortix/kernel/ioctx.h
index e3fd03a5..45fc160a 100644
--- a/sortix/include/sortix/kernel/ioctx.h
+++ b/sortix/include/sortix/kernel/ioctx.h
@@ -37,6 +37,7 @@ struct ioctx_struct
 	gid_t gid, auth_gid;
 	bool (*copy_to_dest)(void* dest, const void* src, size_t n);
 	bool (*copy_from_src)(void* dest, const void* src, size_t n);
+	int dflags;
 };
 
 typedef struct ioctx_struct ioctx_t;
diff --git a/sortix/ioctx.cpp b/sortix/ioctx.cpp
index 92691f97..3d1e5751 100644
--- a/sortix/ioctx.cpp
+++ b/sortix/ioctx.cpp
@@ -38,6 +38,7 @@ void SetupUserIOCtx(ioctx_t* ctx)
 	ctx->gid = ctx->auth_gid = process->gid;
 	ctx->copy_to_dest = CopyToUser;
 	ctx->copy_from_src = CopyFromUser;
+	ctx->dflags = 0;
 }
 
 void SetupKernelIOCtx(ioctx_t* ctx)
@@ -48,6 +49,7 @@ void SetupKernelIOCtx(ioctx_t* ctx)
 	ctx->gid = ctx->auth_gid = process->gid;
 	ctx->copy_to_dest = CopyToKernel;
 	ctx->copy_from_src = CopyFromKernel;
+	ctx->dflags = 0;
 }
 
 } // namespace Sortix