diff --git a/openai/openai.go b/openai/openai.go
index a9169445ef..a01c5d35c2 100644
--- a/openai/openai.go
+++ b/openai/openai.go
@@ -567,18 +567,24 @@ func FromChatRequest(r ChatCompletionRequest) (*api.ChatRequest, error) {
 	}
 
 	var think *api.ThinkValue
+	var effort string
+
 	if r.Reasoning != nil {
-		if !slices.Contains([]string{"high", "medium", "low", "none"}, r.Reasoning.Effort) {
-			return nil, fmt.Errorf("invalid reasoning value: '%s' (must be \"high\", \"medium\", \"low\", or \"none\")", r.Reasoning.Effort)
+		effort = r.Reasoning.Effort
+	} else if r.ReasoningEffort != nil {
+		effort = *r.ReasoningEffort
+	}
+
+	if effort != "" {
+		if !slices.Contains([]string{"high", "medium", "low", "none"}, effort) {
+			return nil, fmt.Errorf("invalid reasoning value: '%s' (must be \"high\", \"medium\", \"low\", or \"none\")", effort)
 		}
 
-		if r.Reasoning.Effort == "none" {
+		if effort == "none" {
 			think = &api.ThinkValue{Value: false}
 		} else {
-			think = &api.ThinkValue{Value: r.Reasoning.Effort}
+			think = &api.ThinkValue{Value: effort}
 		}
-	} else if r.ReasoningEffort != nil {
-		think = &api.ThinkValue{Value: *r.ReasoningEffort}
 	}
 
 	return &api.ChatRequest{