diff --git a/utilities.go b/utilities.go
index 7de6fd6..07fcc9a 100644
--- a/utilities.go
+++ b/utilities.go
@@ -291,19 +291,19 @@ func (t *TraefikOidc) Close() error {
 		}
 
 		if t.httpClient != nil {
-			if transport, ok := t.httpClient.Transport.(*http.Transport); ok {
+			if transport, ok := t.httpClient.Transport.(*http.Transport); ok && transport != nil {
 				transport.CloseIdleConnections()
 				t.safeLogDebug("HTTP client idle connections closed")
 			}
 		}
 
 		if t.tokenHTTPClient != nil {
-			if transport, ok := t.tokenHTTPClient.Transport.(*http.Transport); ok {
+			if transport, ok := t.tokenHTTPClient.Transport.(*http.Transport); ok && transport != nil {
 				transport.CloseIdleConnections()
 				t.safeLogDebug("Token HTTP client idle connections closed")
 			}
 			if t.httpClient == nil || t.tokenHTTPClient.Transport != t.httpClient.Transport {
-				if transport, ok := t.tokenHTTPClient.Transport.(*http.Transport); ok {
+				if transport, ok := t.tokenHTTPClient.Transport.(*http.Transport); ok && transport != nil {
 					transport.CloseIdleConnections()
 					t.safeLogDebug("Token HTTP client transport closed (separate from main)")
 				}