diff --git a/providers/anthropic/anthropic.go b/providers/anthropic/anthropic.go
index 2760b0d71b244b86f46da5d6fce60c094b8a1128..27dd22698532749c9d35ca86e1a9b507dd1eba1f 100644
--- a/providers/anthropic/anthropic.go
+++ b/providers/anthropic/anthropic.go
@@ -1171,6 +1171,9 @@ func (a languageModel) Generate(ctx context.Context, call fantasy.Call) (*fantas
 	if err != nil {
 		return nil, toProviderErr(err)
 	}
+	if response == nil {
+		return nil, &fantasy.Error{Title: "no response", Message: "provider returned nil response"}
+	}
 
 	var content []fantasy.Content
 	for _, block := range response.Content {
diff --git a/providers/openai/language_model.go b/providers/openai/language_model.go
index 4515dabbd9c89e1ab19279b470acd71d5812209d..2907008de13b0ff05150a18aadf01b54d99213ed 100644
--- a/providers/openai/language_model.go
+++ b/providers/openai/language_model.go
@@ -251,6 +251,9 @@ func (o languageModel) Generate(ctx context.Context, call fantasy.Call) (*fantas
 	if err != nil {
 		return nil, toProviderErr(err)
 	}
+	if response == nil {
+		return nil, &fantasy.Error{Title: "no response", Message: "provider returned nil response"}
+	}
 
 	if len(response.Choices) == 0 {
 		return nil, &fantasy.Error{Title: "no response", Message: "no response generated"}
diff --git a/providers/openai/openai_test.go b/providers/openai/openai_test.go
index 254ae635412917fe6c5f9b46db4ec0d9eb6ccabd..2230deae43e26c63435aa0f1235933a661e4b5db 100644
--- a/providers/openai/openai_test.go
+++ b/providers/openai/openai_test.go
@@ -2010,6 +2010,31 @@ func TestDoGenerate(t *testing.T) {
 		require.Equal(t, "ServiceTier", result.Warnings[0].Setting)
 		require.Contains(t, result.Warnings[0].Details, "priority processing is only available")
 	})
+
+	t.Run("should return error instead of panic on empty response body", func(t *testing.T) {
+		t.Parallel()
+
+		server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.WriteHeader(http.StatusOK)
+			// Write empty body — some OpenAI-compatible endpoints may do this
+			// under edge conditions, causing the SDK to return (nil, nil).
+		}))
+		defer server.Close()
+
+		provider, err := New(
+			WithAPIKey("test-api-key"),
+			WithBaseURL(server.URL),
+		)
+		require.NoError(t, err)
+		model, _ := provider.LanguageModel(t.Context(), "gpt-3.5-turbo")
+
+		require.NotPanics(t, func() {
+			_, _ = model.Generate(context.Background(), fantasy.Call{
+				Prompt: testPrompt,
+			})
+		})
+	})
 }
 
 type streamingMockServer struct {
diff --git a/providers/openai/responses_language_model.go b/providers/openai/responses_language_model.go
index 06da0aa6e3d869fffe618bf0cd61c30ea5fa35e8..35c88ed7e55a3df649e25e41ebefcbf67c38aafa 100644
--- a/providers/openai/responses_language_model.go
+++ b/providers/openai/responses_language_model.go
@@ -789,6 +789,9 @@ func (o responsesLanguageModel) Generate(ctx context.Context, call fantasy.Call)
 	if err != nil {
 		return nil, toProviderErr(err)
 	}
+	if response == nil {
+		return nil, &fantasy.Error{Title: "no response", Message: "provider returned nil response"}
+	}
 
 	if response.Error.Message != "" {
 		return nil, &fantasy.Error{