diff --git a/sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/batching/FlowController.java b/sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/batching/FlowController.java
index 3f282b0db7e6..b06b26eed6f2 100644
--- a/sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/batching/FlowController.java
+++ b/sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/batching/FlowController.java
@@ -42,7 +42,9 @@
 public class FlowController {
   /** Base exception that signals a flow control state. */
   public abstract static class FlowControlException extends Exception {
-    private FlowControlException() {}
+    private FlowControlException(String message) {
+      super(message);
+    }
   }
 
   /**
@@ -68,18 +70,13 @@ public static final class MaxOutstandingElementCountReachedException
     private final long currentMaxElementCount;
 
     public MaxOutstandingElementCountReachedException(long currentMaxElementCount) {
+      super("The maximum number of batch elements: " + currentMaxElementCount + " has been reached.");
       this.currentMaxElementCount = currentMaxElementCount;
     }
 
     public long getCurrentMaxBatchElementCount() {
       return currentMaxElementCount;
     }
-
-    @Override
-    public String toString() {
-      return String.format(
-          "The maximum number of batch elements: %d have been reached.", currentMaxElementCount);
-    }
   }
 
   /**
@@ -91,18 +88,13 @@ public static final class MaxOutstandingRequestBytesReachedException
     private final long currentMaxBytes;
 
     public MaxOutstandingRequestBytesReachedException(long currentMaxBytes) {
+      super("The maximum number of batch bytes: " + currentMaxBytes + " has been reached.");
       this.currentMaxBytes = currentMaxBytes;
     }
 
     public long getCurrentMaxBatchBytes() {
       return currentMaxBytes;
     }
-
-    @Override
-    public String toString() {
-      return String.format(
-          "The maximum number of batch bytes: %d have been reached.", currentMaxBytes);
-    }
   }
 
   /**
diff --git a/sdk-platform-java/gax-java/gax/src/test/java/com/google/api/gax/batching/FlowControllerTest.java b/sdk-platform-java/gax-java/gax/src/test/java/com/google/api/gax/batching/FlowControllerTest.java
index c91b5b17aed7..a0062719730c 100644
--- a/sdk-platform-java/gax-java/gax/src/test/java/com/google/api/gax/batching/FlowControllerTest.java
+++ b/sdk-platform-java/gax-java/gax/src/test/java/com/google/api/gax/batching/FlowControllerTest.java
@@ -774,4 +774,18 @@ private List<Future<?>> testConcurrentUpdates(
     executors.shutdown();
     return reserveReleaseFuture;
   }
+
+  @Test
+  public void testExceptionGetMessage() {
+    FlowController.MaxOutstandingElementCountReachedException elementException =
+        new FlowController.MaxOutstandingElementCountReachedException(100);
+    assertThat(elementException.getMessage())
+        .isEqualTo("The maximum number of batch elements: 100 has been reached.");
+
+    FlowController.MaxOutstandingRequestBytesReachedException bytesException =
+        new FlowController.MaxOutstandingRequestBytesReachedException(500);
+    assertThat(bytesException.getMessage())
+        .isEqualTo("The maximum number of batch bytes: 500 has been reached.");
+  }
 }
+