diff --git a/AERO3220_HW4_block_diagram.md b/AERO3220_HW4_block_diagram.md
index f93b88b..e588b04 100644
--- a/AERO3220_HW4_block_diagram.md
+++ b/AERO3220_HW4_block_diagram.md
@@ -95,7 +95,7 @@ flowchart LR
     G2U -->|" + "| S2[Σ]
     Z1 --> G21[Gain k₁/m₂]
     G21 -->|" + "| S2
-    Z2 --> G22[Gain (k₁ + k₂)/m₂]
+    Z2 --> G22["Gain (k₁ + k₂)/m₂"]
     G22 -->|" - "| S2
     Z2D[State ż₂] --> G23[Gain b/m₂]
     G23 -->|" - "| S2