diff --git a/src/companion.rs b/src/companion.rs
index f23f054..8f0128e 100644
--- a/src/companion.rs
+++ b/src/companion.rs
@@ -120,7 +120,7 @@ impl Companion {
     }
 
     /// 記憶に基づく反応メッセージを生成
-    fn generate_reaction_message(&self, memory: &Memory, rarity: &MemoryRarity, user_type: &DiagnosisType) -> String {
+    fn generate_reaction_message(&self, memory: &Memory, rarity: &MemoryRarity, _user_type: &DiagnosisType) -> String {
         let content_preview = if memory.content.len() > 50 {
             format!("{}...", &memory.content[..50])
         } else {
diff --git a/src/mcp/base.rs b/src/mcp/base.rs
index b33df66..2d24c19 100644
--- a/src/mcp/base.rs
+++ b/src/mcp/base.rs
@@ -5,7 +5,6 @@ use std::io::{self, BufRead, Write};
 use crate::memory::MemoryManager;
 use crate::game_formatter::{GameFormatter, DiagnosisType};
 use crate::companion::{Companion, CompanionPersonality, CompanionFormatter};
-use std::sync::{Arc, Mutex};
 
 pub struct BaseMCPServer {
     pub memory_manager: MemoryManager,
diff --git a/src/memory.rs b/src/memory.rs
index acc08b9..62f002c 100644
--- a/src/memory.rs
+++ b/src/memory.rs
@@ -225,7 +225,7 @@ impl MemoryManager {
             .map(|(id, mem)| (id.clone(), mem.priority_score))
             .collect();
 
-        sorted_memories.sort_by(|a, b| a.1.cmp(&b.1));
+        sorted_memories.sort_by(|a, b| a.1.partial_cmp(&b.1).unwrap_or(std::cmp::Ordering::Equal));
 
         let to_remove = self.memories.len() - self.max_memories;
         for (id, _) in sorted_memories.iter().take(to_remove) {