diff --git a/runtime/Java/src/org/antlr/v4/runtime/IntStream.java b/runtime/Java/src/org/antlr/v4/runtime/IntStream.java
index 0b0ca6ff8..53166ee2b 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/IntStream.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/IntStream.java
@@ -79,9 +79,9 @@ public interface IntStream {
 	 * filtering streams (e.g. {@link CommonTokenStream} which distinguishes
 	 * between "on-channel" and "off-channel" tokens).
 	 *
-	 * @throws IllegalStateException if an attempt is made to consume the the
-	 * end of the stream (i.e. if {@code LA(1)==}{@link #EOF EOF} before calling
-	 * {@code consume}).
+	 * @throws IllegalStateException if an attempt is made to consume past
+	 * end of the stream (i.e. if last char == {@link #EOF EOF} before calling
+	 * {@code consume}). Sometimes need to match EOF during prediction.
 	 */
 	void consume();
 
diff --git a/runtime/Java/src/org/antlr/v4/runtime/UnbufferedCharStream.java b/runtime/Java/src/org/antlr/v4/runtime/UnbufferedCharStream.java
index 5f6193b1a..1e98389b2 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/UnbufferedCharStream.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/UnbufferedCharStream.java
@@ -75,7 +75,7 @@ public class UnbufferedCharStream implements CharStream {
 	/**
 	 * This is the {@code LA(-1)} character for the current position.
 	 */
-	protected int lastChar = -1;
+	protected int lastChar = -2; // can't be -1 (EOF)
 
 	/**
 	 * When {@code numMarkers > 0}, this is the {@code LA(-1)} character for the
@@ -129,7 +129,7 @@ public class UnbufferedCharStream implements CharStream {
 
 	@Override
 	public void consume() {
-		if (LA(1) == CharStream.EOF) {
+		if ( lastChar == CharStream.EOF ) {
 			throw new IllegalStateException("cannot consume EOF");
 		}