diff --git a/sortix/dtable.cpp b/sortix/dtable.cpp
index f3786679..40136d3b 100644
--- a/sortix/dtable.cpp
+++ b/sortix/dtable.cpp
@@ -101,12 +101,15 @@ bool DescriptorTable::Enlargen(int atleast)
 	return true;
 }
 
-int DescriptorTable::Allocate(Ref<Descriptor> desc, int flags)
+int DescriptorTable::AllocateInternal(Ref<Descriptor> desc, int flags,
+                                      int min_index)
 {
+	// dtablelock is held.
 	if ( flags & ~__FD_ALLOWED_FLAGS )
 		return errno = EINVAL, -1;
-	ScopedLock lock(&dtablelock);
-	for ( int i = 0; i < numentries; i++ )
+	if ( min_index < 0 )
+		return errno = EINVAL, -1;
+	for ( int i = min_index; i < numentries; i++ )
 		if ( !entries[i].desc )
 		{
 			entries[i].desc = desc;
@@ -114,7 +117,7 @@ int DescriptorTable::Allocate(Ref<Descriptor> desc, int flags)
 			return i;
 		}
 	int oldnumentries = numentries;
-	if ( !Enlargen(0) )
+	if ( !Enlargen(min_index) )
 		return -1;
 	int i = oldnumentries++;
 	entries[i].desc = desc;
@@ -122,6 +125,20 @@ int DescriptorTable::Allocate(Ref<Descriptor> desc, int flags)
 	return i;
 }
 
+int DescriptorTable::Allocate(Ref<Descriptor> desc, int flags, int min_index)
+{
+	ScopedLock lock(&dtablelock);
+	return AllocateInternal(desc, flags, min_index);
+}
+
+int DescriptorTable::Allocate(int src_index, int flags, int min_index)
+{
+	ScopedLock lock(&dtablelock);
+	if ( !IsGoodEntry(src_index) )
+		return errno = EBADF, -1;
+	return AllocateInternal(entries[src_index].desc, flags, min_index);
+}
+
 int DescriptorTable::Copy(int from, int to, int flags)
 {
 	if ( flags & ~__FD_ALLOWED_FLAGS )
diff --git a/sortix/include/sortix/kernel/dtable.h b/sortix/include/sortix/kernel/dtable.h
index 5df265b3..70ae49d4 100644
--- a/sortix/include/sortix/kernel/dtable.h
+++ b/sortix/include/sortix/kernel/dtable.h
@@ -44,7 +44,8 @@ public:
 	~DescriptorTable();
 	Ref<DescriptorTable> Fork();
 	Ref<Descriptor> Get(int index);
-	int Allocate(Ref<Descriptor> desc, int flags);
+	int Allocate(Ref<Descriptor> desc, int flags, int min_index = 0);
+	int Allocate(int src_index, int flags, int min_index = 0);
 	int Copy(int from, int to, int flags);
 	void Free(int index);
 	Ref<Descriptor> FreeKeep(int index);
@@ -56,6 +57,7 @@ private:
 	void Reset(); // Hey, reference counted. Don't call this.
 	bool IsGoodEntry(int i);
 	bool Enlargen(int atleast);
+	int AllocateInternal(Ref<Descriptor> desc, int flags, int min_index);
 
 private:
 	kthread_mutex_t dtablelock;