Index: lucene/core/src/java/org/apache/lucene/store/BufferedIndexInput.java
===================================================================
--- lucene/core/src/java/org/apache/lucene/store/BufferedIndexInput.java	(revision 1307763)
+++ lucene/core/src/java/org/apache/lucene/store/BufferedIndexInput.java	(working copy)
@@ -199,17 +199,17 @@
   public final int readVInt() throws IOException {
     if (5 <= (bufferLength-bufferPosition)) {
       byte b = buffer[bufferPosition++];
+      if (b >= 0) return b;
       int i = b & 0x7F;
-      if ((b & 0x80) == 0) return i;
       b = buffer[bufferPosition++];
       i |= (b & 0x7F) << 7;
-      if ((b & 0x80) == 0) return i;
+      if (b >= 0) return i;
       b = buffer[bufferPosition++];
       i |= (b & 0x7F) << 14;
-      if ((b & 0x80) == 0) return i;
+      if (b >= 0) return i;
       b = buffer[bufferPosition++];
       i |= (b & 0x7F) << 21;
-      if ((b & 0x80) == 0) return i;
+      if (b >= 0) return i;
       b = buffer[bufferPosition++];
       // Warning: the next ands use 0x0F / 0xF0 - beware copy/paste errors:
       i |= (b & 0x0F) << 28;
@@ -224,32 +224,32 @@
   public final long readVLong() throws IOException {
     if (9 <= bufferLength-bufferPosition) {
       byte b = buffer[bufferPosition++];
+      if (b >= 0) return b;
       long i = b & 0x7FL;
-      if ((b & 0x80) == 0) return i;
       b = buffer[bufferPosition++];
       i |= (b & 0x7FL) << 7;
-      if ((b & 0x80) == 0) return i;
+      if (b >= 0) return i;
       b = buffer[bufferPosition++];
       i |= (b & 0x7FL) << 14;
-      if ((b & 0x80) == 0) return i;
+      if (b >= 0) return i;
       b = buffer[bufferPosition++];
       i |= (b & 0x7FL) << 21;
-      if ((b & 0x80) == 0) return i;
+      if (b >= 0) return i;
       b = buffer[bufferPosition++];
       i |= (b & 0x7FL) << 28;
-      if ((b & 0x80) == 0) return i;
+      if (b >= 0) return i;
       b = buffer[bufferPosition++];
       i |= (b & 0x7FL) << 35;
-      if ((b & 0x80) == 0) return i;
+      if (b >= 0) return i;
       b = buffer[bufferPosition++];
       i |= (b & 0x7FL) << 42;
-      if ((b & 0x80) == 0) return i;
+      if (b >= 0) return i;
       b = buffer[bufferPosition++];
       i |= (b & 0x7FL) << 49;
-      if ((b & 0x80) == 0) return i;
+      if (b >= 0) return i;
       b = buffer[bufferPosition++];
       i |= (b & 0x7FL) << 56;
-      if ((b & 0x80) == 0) return i;
+      if (b >= 0) return i;
       throw new IOException("Invalid vLong detected (negative values disallowed)");
     } else {
       return super.readVLong();
Index: lucene/core/src/java/org/apache/lucene/store/ByteArrayDataInput.java
===================================================================
--- lucene/core/src/java/org/apache/lucene/store/ByteArrayDataInput.java	(revision 1307763)
+++ lucene/core/src/java/org/apache/lucene/store/ByteArrayDataInput.java	(working copy)
@@ -102,17 +102,17 @@
   @Override
   public int readVInt() {
     byte b = bytes[pos++];
+    if (b >= 0) return b;
     int i = b & 0x7F;
-    if ((b & 0x80) == 0) return i;
     b = bytes[pos++];
     i |= (b & 0x7F) << 7;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = bytes[pos++];
     i |= (b & 0x7F) << 14;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = bytes[pos++];
     i |= (b & 0x7F) << 21;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = bytes[pos++];
     // Warning: the next ands use 0x0F / 0xF0 - beware copy/paste errors:
     i |= (b & 0x0F) << 28;
@@ -123,32 +123,32 @@
   @Override
   public long readVLong() {
     byte b = bytes[pos++];
+    if (b >= 0) return b;
     long i = b & 0x7FL;
-    if ((b & 0x80) == 0) return i;
     b = bytes[pos++];
     i |= (b & 0x7FL) << 7;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = bytes[pos++];
     i |= (b & 0x7FL) << 14;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = bytes[pos++];
     i |= (b & 0x7FL) << 21;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = bytes[pos++];
     i |= (b & 0x7FL) << 28;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = bytes[pos++];
     i |= (b & 0x7FL) << 35;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = bytes[pos++];
     i |= (b & 0x7FL) << 42;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = bytes[pos++];
     i |= (b & 0x7FL) << 49;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = bytes[pos++];
     i |= (b & 0x7FL) << 56;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     throw new RuntimeException("Invalid vLong detected (negative values disallowed)");
   }
 
Index: lucene/core/src/java/org/apache/lucene/store/DataInput.java
===================================================================
--- lucene/core/src/java/org/apache/lucene/store/DataInput.java	(revision 1307763)
+++ lucene/core/src/java/org/apache/lucene/store/DataInput.java	(working copy)
@@ -94,17 +94,17 @@
     return i;
     */
     byte b = readByte();
+    if (b >= 0) return b;
     int i = b & 0x7F;
-    if ((b & 0x80) == 0) return i;
     b = readByte();
     i |= (b & 0x7F) << 7;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = readByte();
     i |= (b & 0x7F) << 14;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = readByte();
     i |= (b & 0x7F) << 21;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = readByte();
     // Warning: the next ands use 0x0F / 0xF0 - beware copy/paste errors:
     i |= (b & 0x0F) << 28;
@@ -135,32 +135,32 @@
     return i;
     */
     byte b = readByte();
+    if (b >= 0) return b;
     long i = b & 0x7FL;
-    if ((b & 0x80) == 0) return i;
     b = readByte();
     i |= (b & 0x7FL) << 7;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = readByte();
     i |= (b & 0x7FL) << 14;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = readByte();
     i |= (b & 0x7FL) << 21;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = readByte();
     i |= (b & 0x7FL) << 28;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = readByte();
     i |= (b & 0x7FL) << 35;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = readByte();
     i |= (b & 0x7FL) << 42;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = readByte();
     i |= (b & 0x7FL) << 49;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     b = readByte();
     i |= (b & 0x7FL) << 56;
-    if ((b & 0x80) == 0) return i;
+    if (b >= 0) return i;
     throw new IOException("Invalid vLong detected (negative values disallowed)");
   }