diff --git a/fpdf.go b/fpdf.go
index 486de1b..30175fa 100644
--- a/fpdf.go
+++ b/fpdf.go
@@ -3497,6 +3497,7 @@ func (f *Fpdf) getpagesizestr(sizeStr string) (size SizeType) {
 
 		fmt.Println("HALLO")
 		fmt.Println(aString)
+		f.err = fmt.Errorf("HALLO anknown page size %s", sizeStr)
 
 		/*
 			for i := 0; i <= 1; i++ {