diff --git a/flow/pua/flatbuffers_binaryarray.go b/flow/pua/flatbuffers_binaryarray.go
index 50cd5ad46c..635e8f7f55 100644
--- a/flow/pua/flatbuffers_binaryarray.go
+++ b/flow/pua/flatbuffers_binaryarray.go
@@ -85,17 +85,13 @@ func BinaryArraySlice(ls *lua.LState) int {
 	return 1
 }
 
-func (ba *BinaryArray) Grow(newsize int) {
-	newdata := make([]byte, newsize)
-	copy(newdata[newsize-len(ba.data):], ba.data)
-	ba.data = newdata
-}
-
 func BinaryArrayGrow(ls *lua.LState) int {
 	baud, ba := LuaBinaryArray.Check(ls, 1)
 	newsize := int(ls.CheckNumber(2))
 	if newsize > len(ba.data) {
-		ba.Grow(newsize)
+		newdata := make([]byte, newsize)
+		copy(newdata[newsize-len(ba.data):], ba.data)
+		ba.data = newdata
 		baud.Value = ba
 	}
 	return 0
diff --git a/flow/pua/flatbuffers_builder.go b/flow/pua/flatbuffers_builder.go
index 828fbbdcfd..0c024446c9 100644
--- a/flow/pua/flatbuffers_builder.go
+++ b/flow/pua/flatbuffers_builder.go
@@ -1,6 +1,8 @@
 package pua
 
 import (
+	"slices"
+
 	"github.com/yuin/gopher-lua"
 )
 
@@ -58,18 +60,11 @@ func (b *Builder) Prep(width uint8, additional int) {
 	space := alignsize + int(width) + additional
 
 	if b.head < space {
-		oldBufSize := len(b.ba.data)
-		if oldBufSize == 0 {
-			b.ba.data = make([]byte, space)
-			b.head = space
-		} else {
-			newBufSize := oldBufSize
-			for newBufSize < oldBufSize+space {
-				newBufSize *= 2
-			}
-			b.ba.Grow(newBufSize)
-			b.head += newBufSize - oldBufSize
-		}
+		oldlen := len(b.ba.data)
+		newdata := slices.Grow(b.ba.data, space)
+		newdata = newdata[:cap(newdata)]
+		copy(newdata[:oldlen], newdata[len(newdata)-oldlen:])
+		b.head += len(newdata) - oldlen
 	}
 
 	b.Pad(alignsize)
@@ -137,8 +132,8 @@ func (b *Builder) Slot(ls *lua.LState, slotnum int) {
 		ls.RaiseError("Slot called outside nested context")
 		return
 	}
-	for slotnum < len(b.currentVT) {
-		b.currentVT = append(b.currentVT, 0)
+	if slotnum >= len(b.currentVT) {
+		b.currentVT = slices.Grow(b.currentVT, slotnum-len(b.currentVT)+1)
 	}
 	b.currentVT[slotnum] = b.Offset()
 }