diff --git a/packages/web/src/lib/erd.test.ts b/packages/web/src/lib/erd.test.ts
index b40a8008..06102cc9 100644
--- a/packages/web/src/lib/erd.test.ts
+++ b/packages/web/src/lib/erd.test.ts
@@ -141,6 +141,14 @@ describe("ERDModel", () => {
       ).toThrowError("Column 'created__at' must be snake_case.");
     });
 
+    it("should reject identifiers exceeding length limit", () => {
+      model.addTable("users");
+      const longName = "a".repeat(65);
+      expect(() =>
+        model.addColumn("users", { name: longName, type: "integer" }),
+      ).toThrowError("Invalid length for Column identifier.");
+    });
+
     it("should reject invalid SQL default values", () => {
       model.addTable("users");
       expect(() =>
diff --git a/packages/web/src/lib/erd.ts b/packages/web/src/lib/erd.ts
index 0cc436c4..5f48e670 100644
--- a/packages/web/src/lib/erd.ts
+++ b/packages/web/src/lib/erd.ts
@@ -62,7 +62,12 @@ function assertSafeSqlDefaultValue(value: string): void {
   }
 }
 
+const MAX_IDENTIFIER_LENGTH = 64;
+
 function assertSnakeCaseIdentifier(kind: string, name: string): void {
+  if (name.length === 0 || name.length > MAX_IDENTIFIER_LENGTH) {
+    throw new Error(`Invalid length for ${kind} identifier.`);
+  }
   if (!SNAKE_CASE_IDENTIFIER.test(name)) {
     throw new Error(`${kind} '${name}' must be snake_case.`);
   }