diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index f025d84b589..82ad5ae544f 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -58,6 +58,11 @@ New Features
   String is too restrictive (Robert Muir, Shai Erera, Mike
   McCandless)
 
+Bug Fixes
+
+* LUCENE-4998: Fixed a few places to pass IOContext.READONCE instead
+  of IOContext.READ (Shikhar Bhushan via Mike McCandless)
+
 Changes in backwards compatibility policy
 
 * LUCENE-5204: Directory doesn't have default implementations for
diff --git a/lucene/core/src/java/org/apache/lucene/index/CheckIndex.java b/lucene/core/src/java/org/apache/lucene/index/CheckIndex.java
index d0f7bed509e..b22a076153d 100644
--- a/lucene/core/src/java/org/apache/lucene/index/CheckIndex.java
+++ b/lucene/core/src/java/org/apache/lucene/index/CheckIndex.java
@@ -410,7 +410,7 @@ public class CheckIndex {
     // note: we only read the format byte (required preamble) here!
     IndexInput input = null;
     try {
-      input = dir.openInput(segmentsFileName, IOContext.DEFAULT);
+      input = dir.openInput(segmentsFileName, IOContext.READONCE);
     } catch (Throwable t) {
       msg(infoStream, "ERROR: could not open segments file in directory");
       if (infoStream != null)
diff --git a/lucene/core/src/java/org/apache/lucene/index/SegmentReader.java b/lucene/core/src/java/org/apache/lucene/index/SegmentReader.java
index e870166a5a9..11f912c7e7f 100644
--- a/lucene/core/src/java/org/apache/lucene/index/SegmentReader.java
+++ b/lucene/core/src/java/org/apache/lucene/index/SegmentReader.java
@@ -58,7 +58,7 @@ public final class SegmentReader extends AtomicReader {
     try {
       if (si.hasDeletions()) {
         // NOTE: the bitvector is stored using the regular directory, not cfs
-        liveDocs = si.info.getCodec().liveDocsFormat().readLiveDocs(directory(), si, new IOContext(IOContext.READ, true));
+        liveDocs = si.info.getCodec().liveDocsFormat().readLiveDocs(directory(), si, IOContext.READONCE);
       } else {
         assert si.getDelCount() == 0;
         liveDocs = null;
@@ -80,9 +80,9 @@ public final class SegmentReader extends AtomicReader {
   /** Create new SegmentReader sharing core from a previous
    *  SegmentReader and loading new live docs from a new
    *  deletes file.  Used by openIfChanged. */
-  SegmentReader(SegmentInfoPerCommit si, SegmentCoreReaders core, IOContext context) throws IOException {
+  SegmentReader(SegmentInfoPerCommit si, SegmentCoreReaders core) throws IOException {
     this(si, core,
-         si.info.getCodec().liveDocsFormat().readLiveDocs(si.info.dir, si, context),
+         si.info.getCodec().liveDocsFormat().readLiveDocs(si.info.dir, si, IOContext.READONCE),
          si.info.getDocCount() - si.getDelCount());
   }
 
diff --git a/lucene/core/src/java/org/apache/lucene/index/StandardDirectoryReader.java b/lucene/core/src/java/org/apache/lucene/index/StandardDirectoryReader.java
index 7e4316a67ac..493d741e8fb 100644
--- a/lucene/core/src/java/org/apache/lucene/index/StandardDirectoryReader.java
+++ b/lucene/core/src/java/org/apache/lucene/index/StandardDirectoryReader.java
@@ -173,7 +173,7 @@ final class StandardDirectoryReader extends DirectoryReader {
             // Steal the ref returned by SegmentReader ctor:
             assert infos.info(i).info.dir == newReaders[i].getSegmentInfo().info.dir;
             assert infos.info(i).hasDeletions();
-            newReaders[i] = new SegmentReader(infos.info(i), newReaders[i].core, IOContext.READ);
+            newReaders[i] = new SegmentReader(infos.info(i), newReaders[i].core);
           }
         }
         success = true;
diff --git a/lucene/test-framework/src/java/org/apache/lucene/index/BasePostingsFormatTestCase.java b/lucene/test-framework/src/java/org/apache/lucene/index/BasePostingsFormatTestCase.java
index 4cb87e6762c..70db465725e 100644
--- a/lucene/test-framework/src/java/org/apache/lucene/index/BasePostingsFormatTestCase.java
+++ b/lucene/test-framework/src/java/org/apache/lucene/index/BasePostingsFormatTestCase.java
@@ -572,7 +572,7 @@ public abstract class BasePostingsFormatTestCase extends LuceneTestCase {
 
     currentFieldInfos = newFieldInfos;
 
-    SegmentReadState readState = new SegmentReadState(dir, segmentInfo, newFieldInfos, IOContext.DEFAULT);
+    SegmentReadState readState = new SegmentReadState(dir, segmentInfo, newFieldInfos, IOContext.READ);
 
     return codec.postingsFormat().fieldsProducer(readState);
   }