diff --git a/internal/pool/pool.go b/internal/pool/pool.go
index 986c05d0ad..5214448b4b 100644
--- a/internal/pool/pool.go
+++ b/internal/pool/pool.go
@@ -168,9 +168,12 @@ func (p *ConnPool) newConn(ctx context.Context, pooled bool) (*Conn, error) {
 		return nil, ErrClosed
 	}
 
+	p.connsMu.Lock()
 	if p.cfg.MaxActiveConns > 0 && p.poolSize >= p.cfg.MaxActiveConns {
+		p.connsMu.Unlock()
 		return nil, ErrPoolExhausted
 	}
+	p.connsMu.Unlock()
 
 	cn, err := p.dialConn(ctx, pooled)
 	if err != nil {