diff --git a/src/main/java/ellpeck/actuallyadditions/booklet/GuiBooklet.java b/src/main/java/ellpeck/actuallyadditions/booklet/GuiBooklet.java
index 62478f542..6b4e1429a 100644
--- a/src/main/java/ellpeck/actuallyadditions/booklet/GuiBooklet.java
+++ b/src/main/java/ellpeck/actuallyadditions/booklet/GuiBooklet.java
@@ -33,6 +33,7 @@ import java.net.URI;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Locale;
 
 @SideOnly(Side.CLIENT)
 public class GuiBooklet extends GuiScreen{
@@ -185,7 +186,7 @@ public class GuiBooklet extends GuiScreen{
                 currentEntry.chapters.clear();
 
                 for(BookletChapter chapter : currentEntry.allChapters){
-                    if(chapter.getLocalizedName().toLowerCase().contains(this.searchField.getText().toLowerCase())){
+                    if(chapter.getLocalizedName().toLowerCase(Locale.ROOT).contains(this.searchField.getText().toLowerCase(Locale.ROOT))){
                         currentEntry.chapters.add(chapter);
                     }
                 }
diff --git a/src/main/java/ellpeck/actuallyadditions/util/ModUtil.java b/src/main/java/ellpeck/actuallyadditions/util/ModUtil.java
index 1b2f32160..1b9992df6 100644
--- a/src/main/java/ellpeck/actuallyadditions/util/ModUtil.java
+++ b/src/main/java/ellpeck/actuallyadditions/util/ModUtil.java
@@ -13,13 +13,15 @@ package ellpeck.actuallyadditions.util;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
+import java.util.Locale;
+
 public class ModUtil{
 
     public static final String VERSION = "1.7.10-r2";
 
     public static final String MOD_ID = "ActuallyAdditions";
     public static final String NAME = "Actually Additions";
-    public static final String MOD_ID_LOWER = MOD_ID.toLowerCase();
+    public static final String MOD_ID_LOWER = MOD_ID.toLowerCase(Locale.ROOT);
 
     public static final Logger LOGGER = LogManager.getLogger(MOD_ID);
 
diff --git a/src/main/java/ellpeck/actuallyadditions/util/StringUtil.java b/src/main/java/ellpeck/actuallyadditions/util/StringUtil.java
index 3086cbd94..5dba58ca5 100644
--- a/src/main/java/ellpeck/actuallyadditions/util/StringUtil.java
+++ b/src/main/java/ellpeck/actuallyadditions/util/StringUtil.java
@@ -12,6 +12,7 @@ package ellpeck.actuallyadditions.util;
 
 import net.minecraft.util.StatCollector;
 
+import java.util.Locale;
 import java.util.Objects;
 
 public class StringUtil{
@@ -42,7 +43,7 @@ public class StringUtil{
             return null;
         }
         else{
-            return string.toLowerCase();
+            return string.toLowerCase(Locale.ROOT);
         }
     }
 }