diff --git a/LLama/LLamaExecutorBase.cs b/LLama/LLamaExecutorBase.cs
index dbd1b593..2caaa8e5 100644
--- a/LLama/LLamaExecutorBase.cs
+++ b/LLama/LLamaExecutorBase.cs
@@ -68,9 +68,9 @@ namespace LLama
         public LLamaModel Model => _model;
 
         /// <summary>
-        /// Current "mu" value for mirostate sampling
+        /// Current "mu" value for mirostat sampling
         /// </summary>
-        protected float MirostateMu { get; set; } = float.NaN;
+        protected float? MirostatMu { get; set; }
 
         /// <summary>
         /// 
@@ -391,8 +391,8 @@ namespace LLama
             [JsonPropertyName("last_tokens_maximum_count")]
             public int LastTokensCapacity { get; set; }
 
-            [JsonPropertyName("mirostate_mu")]
-            public float MirostateMu { get; set; }
+            [JsonPropertyName("mirostat_mu")]
+            public float? MirostatMu { get; set; }
         }
     }
 }
diff --git a/LLama/LLamaInstructExecutor.cs b/LLama/LLamaInstructExecutor.cs
index 901b347a..7a065ce5 100644
--- a/LLama/LLamaInstructExecutor.cs
+++ b/LLama/LLamaInstructExecutor.cs
@@ -53,7 +53,7 @@ namespace LLama
                 SessionFilePath = _pathSession,
                 SessionTokens = _session_tokens,
                 LastTokensCapacity = _last_n_tokens.Capacity,
-                MirostateMu = MirostateMu
+                MirostatMu = MirostatMu
             };
             return state;
         }
@@ -214,12 +214,12 @@ namespace LLama
                 var tokenDataArray = _model.ApplyPenalty(_last_n_tokens, inferenceParams.LogitBias, repeat_last_n,
                     inferenceParams.RepeatPenalty, inferenceParams.FrequencyPenalty, inferenceParams.PresencePenalty, inferenceParams.PenalizeNL);
 
-                var mu = MirostateMu;
+                var mu = MirostatMu;
                 var id = _model.Sample(
                     tokenDataArray, ref mu, inferenceParams.Temperature, inferenceParams.Mirostat, inferenceParams.MirostatTau,
                     inferenceParams.MirostatEta, inferenceParams.TopK, inferenceParams.TopP, inferenceParams.TfsZ, inferenceParams.TypicalP
                 );
-                MirostateMu = mu;
+                MirostatMu = mu;
 
                 _last_n_tokens.Enqueue(id);
 
diff --git a/LLama/LLamaInteractExecutor.cs b/LLama/LLamaInteractExecutor.cs
index fef6a4d1..52d8d3bc 100644
--- a/LLama/LLamaInteractExecutor.cs
+++ b/LLama/LLamaInteractExecutor.cs
@@ -45,7 +45,7 @@ namespace LLama
                 SessionFilePath = _pathSession,
                 SessionTokens = _session_tokens,
                 LastTokensCapacity = _last_n_tokens.Capacity,
-                MirostateMu = MirostateMu
+                MirostatMu = MirostatMu
             };
             return state;
         }
@@ -203,12 +203,12 @@ namespace LLama
                 var tokenDataArray = _model.ApplyPenalty(_last_n_tokens, inferenceParams.LogitBias, repeat_last_n,
                     inferenceParams.RepeatPenalty, inferenceParams.FrequencyPenalty, inferenceParams.PresencePenalty, inferenceParams.PenalizeNL);
 
-                var mu = MirostateMu;
+                var mu = MirostatMu;
                 var id = _model.Sample(
                     tokenDataArray, ref mu, inferenceParams.Temperature, inferenceParams.Mirostat, inferenceParams.MirostatTau, 
                     inferenceParams.MirostatEta, inferenceParams.TopK, inferenceParams.TopP, inferenceParams.TfsZ, inferenceParams.TypicalP
                 );
-                MirostateMu = mu;
+                MirostatMu = mu;
 
                 _last_n_tokens.Enqueue(id);
 
diff --git a/LLama/LLamaModel.cs b/LLama/LLamaModel.cs
index 526ffcb2..4bcf0fec 100644
--- a/LLama/LLamaModel.cs
+++ b/LLama/LLamaModel.cs
@@ -228,7 +228,7 @@ namespace LLama
         /// <param name="tfsZ"></param>
         /// <param name="typicalP"></param>
         /// <returns></returns>
-        public llama_token Sample(LLamaTokenDataArray candidates, ref float mirostat_mu, float temperature = 0.8f, MirostatType mirostat = MirostatType.Disable, 
+        public llama_token Sample(LLamaTokenDataArray candidates, ref float? mirostat_mu, float temperature = 0.8f, MirostatType mirostat = MirostatType.Disable, 
                                   float mirostatTau = 5.0f, float mirostatEta = 0.1f, int topK = 40, float topP = 0.95f, float tfsZ = 1.0f, float typicalP = 1.0f)
         {
             llama_token id;
@@ -239,30 +239,31 @@ namespace LLama
             }
             else
             {
-                if (float.IsNaN(mirostat_mu))
-                    mirostat_mu = 2 * mirostatTau;
-
-                if (mirostat == MirostatType.Mirostat)
-                {
-                    const int mirostat_m = 100;
-                    SamplingApi.llama_sample_temperature(_ctx, candidates, temperature);
-                    id = SamplingApi.llama_sample_token_mirostat(_ctx, candidates, mirostatTau, mirostatEta, mirostat_m, ref mirostat_mu);
-                }
-                else if (mirostat == MirostatType.Mirostat2)
-                {
-                    SamplingApi.llama_sample_temperature(_ctx, candidates, temperature);
-                    id = SamplingApi.llama_sample_token_mirostat_v2(_ctx, candidates, mirostatTau, mirostatEta, ref mirostat_mu);
-                }
-                else
+                var mu = mirostat_mu ?? (2 * mirostatTau);
                 {
-                    // Temperature sampling
-                    SamplingApi.llama_sample_top_k(_ctx, candidates, topK, 1);
-                    SamplingApi.llama_sample_tail_free(_ctx, candidates, tfsZ, 1);
-                    SamplingApi.llama_sample_typical(_ctx, candidates, typicalP, 1);
-                    SamplingApi.llama_sample_top_p(_ctx, candidates, topP, 1);
-                    SamplingApi.llama_sample_temperature(_ctx, candidates, temperature);
-                    id = SamplingApi.llama_sample_token(_ctx, candidates);
+                    if (mirostat == MirostatType.Mirostat)
+                    {
+                        const int mirostat_m = 100;
+                        SamplingApi.llama_sample_temperature(_ctx, candidates, temperature);
+                        id = SamplingApi.llama_sample_token_mirostat(_ctx, candidates, mirostatTau, mirostatEta, mirostat_m, ref mu);
+                    }
+                    else if (mirostat == MirostatType.Mirostat2)
+                    {
+                        SamplingApi.llama_sample_temperature(_ctx, candidates, temperature);
+                        id = SamplingApi.llama_sample_token_mirostat_v2(_ctx, candidates, mirostatTau, mirostatEta, ref mu);
+                    }
+                    else
+                    {
+                        // Temperature sampling
+                        SamplingApi.llama_sample_top_k(_ctx, candidates, topK, 1);
+                        SamplingApi.llama_sample_tail_free(_ctx, candidates, tfsZ, 1);
+                        SamplingApi.llama_sample_typical(_ctx, candidates, typicalP, 1);
+                        SamplingApi.llama_sample_top_p(_ctx, candidates, topP, 1);
+                        SamplingApi.llama_sample_temperature(_ctx, candidates, temperature);
+                        id = SamplingApi.llama_sample_token(_ctx, candidates);
+                    }
                 }
+                mirostat_mu = mu;
             }
             return id;
         }
diff --git a/LLama/LLamaStatelessExecutor.cs b/LLama/LLamaStatelessExecutor.cs
index 9075edd1..be32a5af 100644
--- a/LLama/LLamaStatelessExecutor.cs
+++ b/LLama/LLamaStatelessExecutor.cs
@@ -57,7 +57,7 @@ namespace LLama
             lastTokens.AddRange(tokens);
             n_past += n_prompt_tokens;
 
-            var mu = float.NaN;
+            var mu = (float?)null;
             int max_tokens = inferenceParams.MaxTokens < 0 ? int.MaxValue : inferenceParams.MaxTokens;
             for(int i = 0; i < max_tokens; i++)
             {