diff --git a/AERO3220_HW4_block_diagram.md b/AERO3220_HW4_block_diagram.md
index ef5cc5b..6aa14fb 100644
--- a/AERO3220_HW4_block_diagram.md
+++ b/AERO3220_HW4_block_diagram.md
@@ -95,7 +95,7 @@ flowchart LR
     G2U --> S2[Sum z2ddot]
     Z1 --> G21[Gain k1/m2]
     G21 --> S2
-    Z2 --> G22[Gain -(k1+k2)/m2]
+    Z2 --> G22["Gain -(k1 + k2)/m2"]
     G22 --> S2
     Z2D[State z2dot] --> G23[Gain -b/m2]
     G23 --> S2