diff --git a/api/client.go b/api/client.go
index b2f4638ab..9e9a848e3 100644
--- a/api/client.go
+++ b/api/client.go
@@ -660,7 +660,7 @@ func (c *Client) NewRequest(ctx context.Context, method, requestPath string, bod
 			return nil, fmt.Errorf("error performing SRV lookup of http:tcp:%s : %w", u.Hostname(), err)
 		}
 		if len(addrs) > 0 {
-			host = fmt.Sprintf("%s:%d", addrs[0].Target, addrs[0].Port)
+			host = net.JoinHostPort(addrs[0].Target, fmt.Sprintf("%d", addrs[0].Port))
 		}
 	}
 
diff --git a/internal/daemon/worker/testing.go b/internal/daemon/worker/testing.go
index b7096ab9c..fdf0bec93 100644
--- a/internal/daemon/worker/testing.go
+++ b/internal/daemon/worker/testing.go
@@ -74,7 +74,7 @@ func (tw *TestWorker) ProxyAddrs() []string {
 			if !ok {
 				tw.t.Fatal("could not parse address as a TCP addr")
 			}
-			addr := fmt.Sprintf("%s:%d", tcpAddr.IP.String(), tcpAddr.Port)
+			addr := net.JoinHostPort(tcpAddr.IP.String(), fmt.Sprintf("%d", tcpAddr.Port))
 			tw.addrs = append(tw.addrs, addr)
 		}
 	}