diff --git a/runtime/Java/src/org/antlr/v4/runtime/ANTLRFileStream.java b/runtime/Java/src/org/antlr/v4/runtime/ANTLRFileStream.java
index 6a74ee479..f66e48211 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/ANTLRFileStream.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/ANTLRFileStream.java
@@ -33,6 +33,7 @@ import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.util.Arrays;
 
 /** This is an ANTLRInputStream that is loaded from a file
  *  all at once when you construct the object.  This is a special case
@@ -69,7 +70,10 @@ public class ANTLRFileStream extends ANTLRInputStream {
 		}
 		try {
 			data = new char[size];
-			super.n = isr.read(data);
+			n = isr.read(data);
+			if (n < data.length) {
+				data = Arrays.copyOf(data, n);
+			}
 		}
 		finally {
 			isr.close();