diff --git a/fpdf.go b/fpdf.go
index ce07961..07f80a7 100644
--- a/fpdf.go
+++ b/fpdf.go
@@ -3489,7 +3489,7 @@ func (f *Fpdf) getpagesizestr(sizeStr string) (size SizeType) {
 	if strings.Contains(sizeStr, "x") {
 
 		var (
-			aString [2]string
+			aString []string
 			aFloat  [2]float64
 			aErr    error
 		)