diff --git a/nifi-mock/src/main/java/org/apache/nifi/util/MockProcessSession.java b/nifi-mock/src/main/java/org/apache/nifi/util/MockProcessSession.java
index 7bf9a03af2..fe9faf9ff8 100644
--- a/nifi-mock/src/main/java/org/apache/nifi/util/MockProcessSession.java
+++ b/nifi-mock/src/main/java/org/apache/nifi/util/MockProcessSession.java
@@ -618,6 +618,11 @@ public class MockProcessSession implements ProcessSession {
                 bais.reset();
             }
 
+            @Override
+            public int available() throws IOException {
+                return bais.available();
+            }
+
             @Override
             public String toString() {
                 return "ErrorHandlingInputStream[flowFile=" + mock + "]";