diff --git a/library/core/src/main/java/com/google/android/exoplayer2/Timeline.java b/library/core/src/main/java/com/google/android/exoplayer2/Timeline.java
index 7ce23e67ece..414c0804ad2 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/Timeline.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/Timeline.java
@@ -95,7 +95,7 @@
  * of the on-demand stream ends, playback of the live stream will start from its default position
  * near the live edge.
  *
- * <h3 id="single-file">On-demand stream with mid-roll ads</h3>
+ * <h3 id="single-file-midrolls">On-demand stream with mid-roll ads</h3>
  * <p align="center">
  *   <img src="doc-files/timeline-single-file-midrolls.svg" alt="Example timeline for an on-demand
  *       stream with mid-roll ad groups">
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/text/ssa/SsaDecoder.java b/library/core/src/main/java/com/google/android/exoplayer2/text/ssa/SsaDecoder.java
index 11489e7b35a..d2f5a67c279 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/text/ssa/SsaDecoder.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/text/ssa/SsaDecoder.java
@@ -23,6 +23,7 @@
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.LongArray;
 import com.google.android.exoplayer2.util.ParsableByteArray;
+import com.google.android.exoplayer2.util.Util;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.regex.Matcher;
@@ -132,7 +133,7 @@ private void parseFormatLine(String formatLine) {
     formatEndIndex = C.INDEX_UNSET;
     formatTextIndex = C.INDEX_UNSET;
     for (int i = 0; i < formatKeyCount; i++) {
-      String key = values[i].trim().toLowerCase();
+      String key = Util.toLowerInvariant(values[i].trim());
       switch (key) {
         case "start":
           formatStartIndex = i;
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlDecoder.java b/library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlDecoder.java
index e438aa18378..a215bf3cc9a 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlDecoder.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlDecoder.java
@@ -290,7 +290,7 @@ private TtmlRegion parseRegionAttributes(XmlPullParser xmlParser) {
     String displayAlign = XmlPullParserUtil.getAttributeValue(xmlParser,
         TtmlNode.ATTR_TTS_DISPLAY_ALIGN);
     if (displayAlign != null) {
-      switch (displayAlign.toLowerCase()) {
+      switch (Util.toLowerInvariant(displayAlign)) {
         case "center":
           lineAnchor = Cue.ANCHOR_TYPE_MIDDLE;
           line += height / 2;
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/util/Util.java b/library/core/src/main/java/com/google/android/exoplayer2/util/Util.java
index c00d7fa36c0..b958a54244c 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/util/Util.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/util/Util.java
@@ -895,7 +895,7 @@ public static int inferContentType(Uri uri) {
    */
   @C.ContentType
   public static int inferContentType(String fileName) {
-    fileName = fileName.toLowerCase();
+    fileName = Util.toLowerInvariant(fileName);
     if (fileName.endsWith(".mpd")) {
       return C.TYPE_DASH;
     } else if (fileName.endsWith(".m3u8")) {
diff --git a/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsChunkSource.java b/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsChunkSource.java
index 38c3da81947..bca62ed2303 100644
--- a/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsChunkSource.java
+++ b/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsChunkSource.java
@@ -39,7 +39,6 @@
 import java.math.BigInteger;
 import java.util.Arrays;
 import java.util.List;
-import java.util.Locale;
 
 /**
  * Source of Hls (possibly adaptive) chunks.
@@ -366,7 +365,7 @@ private EncryptionKeyChunk newEncryptionKeyChunk(Uri keyUri, String iv, int vari
 
   private void setEncryptionData(Uri keyUri, String iv, byte[] secretKey) {
     String trimmedIv;
-    if (iv.toLowerCase(Locale.getDefault()).startsWith("0x")) {
+    if (Util.toLowerInvariant(iv).startsWith("0x")) {
       trimmedIv = iv.substring(2);
     } else {
       trimmedIv = iv;
diff --git a/library/ui/src/main/java/com/google/android/exoplayer2/ui/DebugTextViewHelper.java b/library/ui/src/main/java/com/google/android/exoplayer2/ui/DebugTextViewHelper.java
index 8c4bad18628..060780eda2f 100644
--- a/library/ui/src/main/java/com/google/android/exoplayer2/ui/DebugTextViewHelper.java
+++ b/library/ui/src/main/java/com/google/android/exoplayer2/ui/DebugTextViewHelper.java
@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.ui;
 
+import android.annotation.SuppressLint;
 import android.widget.TextView;
 import com.google.android.exoplayer2.ExoPlaybackException;
 import com.google.android.exoplayer2.Format;
@@ -25,6 +26,7 @@
 import com.google.android.exoplayer2.decoder.DecoderCounters;
 import com.google.android.exoplayer2.source.TrackGroupArray;
 import com.google.android.exoplayer2.trackselection.TrackSelectionArray;
+import java.util.Locale;
 
 /**
  * A helper class for periodically updating a {@link TextView} with debug information obtained from
@@ -125,6 +127,7 @@ public void run() {
 
   // Private methods.
 
+  @SuppressLint("SetTextI18n")
   private void updateAndPost() {
     textView.setText(getPlayerStateString() + getPlayerWindowIndexString() + getVideoString()
         + getAudioString());
@@ -192,7 +195,7 @@ private static String getDecoderCountersBufferCountString(DecoderCounters counte
 
   private static String getPixelAspectRatioString(float pixelAspectRatio) {
     return pixelAspectRatio == Format.NO_VALUE || pixelAspectRatio == 1f ? ""
-        : (" par:" + String.format("%.02f", pixelAspectRatio));
+        : (" par:" + String.format(Locale.US, "%.02f", pixelAspectRatio));
   }
 
 }