diff --git a/internal/pool/pool.go b/internal/pool/pool.go
index 4cdcff2f..ff946424 100644
--- a/internal/pool/pool.go
+++ b/internal/pool/pool.go
@@ -310,6 +310,12 @@ func (p *ConnPool) popIdle() *Conn {
 }
 
 func (p *ConnPool) Put(cn *Conn) {
+	if cn.rd.Buffered() > 0 {
+		internal.Logger.Printf("Conn has unread data")
+		p.Remove(cn, BadConnError{})
+		return
+	}
+
 	if !cn.pooled {
 		p.Remove(cn, nil)
 		return
diff --git a/internal/proto/reader.go b/internal/proto/reader.go
index 7a2777ee..a48f1ae7 100644
--- a/internal/proto/reader.go
+++ b/internal/proto/reader.go
@@ -41,6 +41,10 @@ func NewReader(rd io.Reader) *Reader {
 	}
 }
 
+func (r *Reader) Buffered() int {
+	return r.rd.Buffered()
+}
+
 func (r *Reader) Reset(rd io.Reader) {
 	r.rd.Reset(rd)
 }