diff --git a/wpilibj/src/main/java/edu/wpi/first/wpilibj/simulation/DifferentialDrivetrainSim.java b/wpilibj/src/main/java/edu/wpi/first/wpilibj/simulation/DifferentialDrivetrainSim.java
index 2e608bc36c..ab3d003d1c 100644
--- a/wpilibj/src/main/java/edu/wpi/first/wpilibj/simulation/DifferentialDrivetrainSim.java
+++ b/wpilibj/src/main/java/edu/wpi/first/wpilibj/simulation/DifferentialDrivetrainSim.java
@@ -98,6 +98,7 @@ public class DifferentialDrivetrainSim {
     m_currentGearing = m_originalGearing;
 
     m_x = new Matrix<>(Nat.N7(), Nat.N1());
+    m_u = VecBuilder.fill(0, 0);
   }
 
   /**