diff --git a/wpilibc/src/main/native/include/frc2/Timer.h b/wpilibc/src/main/native/include/frc2/Timer.h
index 82668ba42f..9c616fa02b 100644
--- a/wpilibc/src/main/native/include/frc2/Timer.h
+++ b/wpilibc/src/main/native/include/frc2/Timer.h
@@ -75,7 +75,8 @@ class Timer {
    * Start the timer running.
    *
    * Just set the running flag to true indicating that all time requests should
-   * be relative to the system clock.
+   * be relative to the system clock. Note that this method is a no-op if the
+   * timer is already running.
    */
   void Start();
 
diff --git a/wpilibj/src/main/java/edu/wpi/first/wpilibj/Timer.java b/wpilibj/src/main/java/edu/wpi/first/wpilibj/Timer.java
index d08d601c2c..43b40cfcb8 100644
--- a/wpilibj/src/main/java/edu/wpi/first/wpilibj/Timer.java
+++ b/wpilibj/src/main/java/edu/wpi/first/wpilibj/Timer.java
@@ -96,12 +96,15 @@ public class Timer {
 
   /**
    * Start the timer running. Just set the running flag to true indicating that all time requests
-   * should be relative to the system clock.
+   * should be relative to the system clock. Note that this method is a no-op if the timer is
+   * already running.
    */
   public void start() {
     synchronized (m_lock) {
-      m_startTime = getMsClock();
-      m_running = true;
+      if (!m_running) {
+        m_startTime = getMsClock();
+        m_running = true;
+      }
     }
   }