diff --git a/proto/generate.proto b/proto/generate.proto
index 11455fee..8f431c5c 100644
--- a/proto/generate.proto
+++ b/proto/generate.proto
@@ -31,7 +31,7 @@ message NextTokenChooserParameters {
     /// exponential scaling output probability distribution
     float temperature = 1;
     /// restricting to the k highest probability elements
-    int32 top_k = 2;
+    uint32 top_k = 2;
     /// restricting to top tokens summing to prob_cut_off <= prob_cut_off
     float top_p = 3;
     /// apply sampling on the logits
diff --git a/router/src/validation.rs b/router/src/validation.rs
index 99a5a975..39da2a83 100644
--- a/router/src/validation.rs
+++ b/router/src/validation.rs
@@ -156,7 +156,7 @@ fn validate(
 
                 let parameters = NextTokenChooserParameters {
                     temperature,
-                    top_k,
+                    top_k: top_k as u32,
                     top_p,
                     do_sample,
                     seed,