diff --git a/providers/openai/language_model_hooks.go b/providers/openai/language_model_hooks.go
index 686c655d5c5c03f44e1aefd47abb29eb36499d44..576dcf46ebc8375ec0a74547ff7b5969c9fd692f 100644
--- a/providers/openai/language_model_hooks.go
+++ b/providers/openai/language_model_hooks.go
@@ -262,6 +262,9 @@ func DefaultStreamUsageFunc(chunk openai.ChatCompletionChunk, _ map[string]any,
 
 // DefaultStreamProviderMetadataFunc is the default implementation for handling stream provider metadata.
 func DefaultStreamProviderMetadataFunc(choice openai.ChatCompletionChoice, metadata fantasy.ProviderMetadata) fantasy.ProviderMetadata {
+	if metadata == nil {
+		metadata = fantasy.ProviderMetadata{}
+	}
 	streamProviderMetadata, ok := metadata[Name]
 	if !ok {
 		streamProviderMetadata = &ProviderMetadata{}