diff --git a/mcp/transport.go b/mcp/transport.go
index 1d6a831..d65e804 100644
--- a/mcp/transport.go
+++ b/mcp/transport.go
@@ -21,8 +21,9 @@ func NewSTDIOTransport(command string, args []string, env map[string]string) *ST
 // Connect launches the subprocess and returns a connected Client.
 func (t *STDIOTransport) Connect() (*Client, error) {
 	cmd := exec.Command(t.command, t.args...)
+	cmd.Env = os.Environ()
 	for k, v := range t.env {
-		cmd.Env = append(os.Environ(), fmt.Sprintf("%s=%s", k, v))
+		cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%s", k, v))
 	}
 
 	stdin, err := cmd.StdinPipe()