diff --git a/src/infrastructure/update-check.ts b/src/infrastructure/update-check.ts
index b0199892..d8438088 100644
--- a/src/infrastructure/update-check.ts
+++ b/src/infrastructure/update-check.ts
@@ -18,11 +18,11 @@ interface UpdateCache {
 
 /**
  * Minimal semver comparison. Returns -1, 0, or 1.
- * Only handles numeric x.y.z (no pre-release tags).
+ * Strips pre-release suffixes (e.g. "3.9.3-dev.6" → "3.9.3") before comparing.
  */
 export function semverCompare(a: string, b: string): -1 | 0 | 1 {
-  const pa = a.split('.').map(Number);
-  const pb = b.split('.').map(Number);
+  const pa = a.replace(/-.*$/, '').split('.').map(Number);
+  const pb = b.replace(/-.*$/, '').split('.').map(Number);
   for (let i = 0; i < 3; i++) {
     const na = pa[i] || 0;
     const nb = pb[i] || 0;
diff --git a/tests/unit/update-check.test.ts b/tests/unit/update-check.test.ts
index 46621d8b..abb35aad 100644
--- a/tests/unit/update-check.test.ts
+++ b/tests/unit/update-check.test.ts
@@ -51,6 +51,15 @@ describe('semverCompare', () => {
   it('major takes priority over minor and patch', () => {
     expect(semverCompare('1.9.9', '2.0.0')).toBe(-1);
   });
+
+  it('strips pre-release suffixes before comparing', () => {
+    // 3.9.3-dev.6 should be treated as 3.9.3, which is > 3.9.1
+    expect(semverCompare('3.9.3-dev.6', '3.9.1')).toBe(1);
+    expect(semverCompare('3.9.3-dev.6', '3.9.3')).toBe(0);
+    expect(semverCompare('3.9.3-dev.6', '3.9.4')).toBe(-1);
+    // Both sides with pre-release
+    expect(semverCompare('2.0.0-beta.1', '1.9.9-alpha.3')).toBe(1);
+  });
 });
 
 // ─── checkForUpdates ────────────────────────────────────────────────