diff --git a/common/crypto/auth.go b/common/crypto/auth.go
index ec197cee..fd8a9df0 100644
--- a/common/crypto/auth.go
+++ b/common/crypto/auth.go
@@ -139,7 +139,8 @@ func (v *AuthenticationReader) EnsureChunk() error {
 					return copy(b, leftover), nil
 				})
 			}
-			if err := v.buffer.AppendSupplier(buf.ReadFrom(v.reader)); err == nil {
+			err = v.buffer.AppendSupplier(buf.ReadFrom(v.reader))
+			if err == nil {
 				continue
 			}
 		}