diff --git a/lib/std/io/stream/bytebuffer.c3 b/lib/std/io/stream/bytebuffer.c3
index e550befdf..a81d886e5 100644
--- a/lib/std/io/stream/bytebuffer.c3
+++ b/lib/std/io/stream/bytebuffer.c3
@@ -130,7 +130,7 @@ fn usz? ByteBuffer.available(&self) @inline @dynamic
 
 fn void ByteBuffer.grow(&self, usz n)
 {
-	n = math::next_power_of_2(n);
+	n = math::next_power_of_2(self.bytes.len + n);
 	char* p = allocator::realloc(self.allocator, self.bytes, n);
 	self.bytes = p[:n];
 }
diff --git a/releasenotes.md b/releasenotes.md
index 41898e94d..02758786d 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -9,6 +9,7 @@
 - Regression with npot vector in struct triggering an assert #2219.
 - Casting bitstruct to wider base type should be single step #2616.
 - Optional does not play well with bit ops #2618.
+- `Bytebuffer.grow` was broken #2622.
 
 ### Stdlib changes