diff --git a/querydsl-core/src/main/java/com/querydsl/core/types/ExpressionUtils.java b/querydsl-core/src/main/java/com/querydsl/core/types/ExpressionUtils.java
index 36a68976b..5824c7e03 100644
--- a/querydsl-core/src/main/java/com/querydsl/core/types/ExpressionUtils.java
+++ b/querydsl-core/src/main/java/com/querydsl/core/types/ExpressionUtils.java
@@ -900,7 +900,7 @@ public final class ExpressionUtils {
     public static Expression<String> toLower(Expression<String> stringExpression) {
         if (stringExpression instanceof Constant) {
             Constant<String> constantExpression = (Constant<String>) stringExpression;
-            return ConstantImpl.create(constantExpression.getConstant().toLowerCase(Locale.ENGLISH));
+            return ConstantImpl.create(constantExpression.getConstant().toLowerCase());
         } else {
             return operation(String.class, Ops.LOWER, stringExpression);
         }
diff --git a/querydsl-core/src/main/java/com/querydsl/core/types/TemplateFactory.java b/querydsl-core/src/main/java/com/querydsl/core/types/TemplateFactory.java
index c6dca7dd9..2e39fb0c0 100644
--- a/querydsl-core/src/main/java/com/querydsl/core/types/TemplateFactory.java
+++ b/querydsl-core/src/main/java/com/querydsl/core/types/TemplateFactory.java
@@ -60,7 +60,7 @@ public class TemplateFactory {
                     } else if (arg instanceof Expression) {
                         return ExpressionUtils.operation(String.class, Ops.LOWER, (Expression) arg);
                     } else {
-                        return String.valueOf(arg).toLowerCase(Locale.ENGLISH);
+                        return String.valueOf(arg).toLowerCase();
                     }
                 }
             };
@@ -74,7 +74,7 @@ public class TemplateFactory {
                     } else if (arg instanceof Expression) {
                         return ExpressionUtils.operation(String.class, Ops.UPPER, (Expression) arg);
                     } else {
-                        return String.valueOf(arg).toUpperCase(Locale.ENGLISH);
+                        return String.valueOf(arg).toUpperCase();
                     }
                 }
             };
@@ -103,7 +103,7 @@ public class TemplateFactory {
                         Expression<String> concatenated = ExpressionUtils.operation(String.class, Ops.CONCAT, (Expression) arg, PERCENT);
                         return ExpressionUtils.operation(String.class, Ops.LOWER, concatenated);
                     } else {
-                        return escapeForLike(String.valueOf(arg).toLowerCase(Locale.ENGLISH)) + "%";
+                        return escapeForLike(String.valueOf(arg).toLowerCase()) + "%";
                     }
                 }
             };
@@ -132,7 +132,7 @@ public class TemplateFactory {
                         Expression<String> concatenated = ExpressionUtils.operation(String.class, Ops.CONCAT, PERCENT, (Expression) arg);
                         return ExpressionUtils.operation(String.class, Ops.LOWER, concatenated);
                     } else {
-                        return "%" + escapeForLike(String.valueOf(arg).toLowerCase(Locale.ENGLISH));
+                        return "%" + escapeForLike(String.valueOf(arg).toLowerCase());
                     }
                 }
             };
@@ -163,7 +163,7 @@ public class TemplateFactory {
                         concatenated = ExpressionUtils.operation(String.class, Ops.CONCAT, concatenated, PERCENT);
                         return ExpressionUtils.operation(String.class, Ops.LOWER, concatenated);
                     } else {
-                        return "%" + escapeForLike(String.valueOf(arg).toLowerCase(Locale.ENGLISH)) + "%";
+                        return "%" + escapeForLike(String.valueOf(arg).toLowerCase()) + "%";
                     }
                 }
             };
diff --git a/querydsl-core/src/test/java/com/querydsl/core/StringConstant.java b/querydsl-core/src/test/java/com/querydsl/core/StringConstant.java
index 3ef7ee2de..600b07c25 100644
--- a/querydsl-core/src/test/java/com/querydsl/core/StringConstant.java
+++ b/querydsl-core/src/test/java/com/querydsl/core/StringConstant.java
@@ -13,8 +13,6 @@
  */
 package com.querydsl.core;
 
-import java.util.Locale;
-
 import javax.annotation.Nullable;
 
 import com.querydsl.core.types.Constant;
@@ -118,7 +116,7 @@ public final class StringConstant extends StringExpression implements Constant<S
     @Override
     public StringExpression lower() {
         if (lower == null) {
-            lower = new StringConstant(constant.toLowerCase(Locale.ENGLISH));
+            lower = new StringConstant(constant.toLowerCase());
         }
         return lower;
     }
@@ -178,7 +176,7 @@ public final class StringConstant extends StringExpression implements Constant<S
     @Override
     public StringExpression upper() {
         if (upper == null) {
-            upper = new StringConstant(constant.toUpperCase(Locale.ENGLISH));
+            upper = new StringConstant(constant.toUpperCase());
         }
         return upper;
     }
diff --git a/querydsl-sql/src/main/java/com/querydsl/sql/SQLSerializer.java b/querydsl-sql/src/main/java/com/querydsl/sql/SQLSerializer.java
index 300450666..b8756953e 100644
--- a/querydsl-sql/src/main/java/com/querydsl/sql/SQLSerializer.java
+++ b/querydsl-sql/src/main/java/com/querydsl/sql/SQLSerializer.java
@@ -177,7 +177,7 @@ public class SQLSerializer extends SerializerBase<SQLSerializer> {
             for (Expression<?> expr : expressions) {
                 if (expr instanceof Path) {
                     String name = ColumnMetadata.getName((Path<?>) expr);
-                    if (!names.add(name.toLowerCase(Locale.ENGLISH))) {
+                    if (!names.add(name.toLowerCase())) {
                         expr = ExpressionUtils.as(expr, "col__" + name + replacements.size());
                     }
                 }
diff --git a/querydsl-sql/src/test/java/com/querydsl/sql/SelectBase.java b/querydsl-sql/src/test/java/com/querydsl/sql/SelectBase.java
index 259df3813..efc5f206c 100644
--- a/querydsl-sql/src/test/java/com/querydsl/sql/SelectBase.java
+++ b/querydsl-sql/src/test/java/com/querydsl/sql/SelectBase.java
@@ -1689,6 +1689,18 @@ public class SelectBase extends AbstractBaseTest {
         standardTest.report();
     }
 
+    @Test
+    @IncludeIn(H2)
+    public void standardTest_turkish() {
+        Locale defaultLocale = Locale.getDefault();
+        Locale.setDefault(new Locale("tr", "TR"));
+        try {
+            standardTest();
+        } finally {
+            Locale.setDefault(defaultLocale);
+        }
+    }
+
     @Test
     @ExcludeIn(SQLITE)
     public void string() {