diff --git a/runtime-parent/runtime-compute/src/main/java/com/speedment/runtime/compute/ToChar.java b/runtime-parent/runtime-compute/src/main/java/com/speedment/runtime/compute/ToChar.java
index 548be62991..c4fbc868b5 100644
--- a/runtime-parent/runtime-compute/src/main/java/com/speedment/runtime/compute/ToChar.java
+++ b/runtime-parent/runtime-compute/src/main/java/com/speedment/runtime/compute/ToChar.java
@@ -34,6 +34,7 @@ public interface ToChar<T>
         HasAsInt<T>,
         HasAsLong<T>,
         HasMap<T, CharUnaryOperator, ToChar<T>>,
+        HasCase<T, ToChar<T>>,
         HasHash<T>,
         HasCompare<T>,
         HasCompose<T> {
@@ -81,10 +82,12 @@ default ToChar<T> map(CharUnaryOperator operator) {
         return MapperUtil.map(this, operator);
     }
 
+    @Override
     default ToChar<T> toUpperCase() {
         return map(Character::toUpperCase);
     }
 
+    @Override
     default ToChar<T> toLowerCase() {
         return map(Character::toLowerCase);
     }
diff --git a/runtime-parent/runtime-compute/src/main/java/com/speedment/runtime/compute/ToString.java b/runtime-parent/runtime-compute/src/main/java/com/speedment/runtime/compute/ToString.java
index 4655bb7a8d..3ee4907624 100644
--- a/runtime-parent/runtime-compute/src/main/java/com/speedment/runtime/compute/ToString.java
+++ b/runtime-parent/runtime-compute/src/main/java/com/speedment/runtime/compute/ToString.java
@@ -4,6 +4,7 @@
 import com.speedment.runtime.compute.expression.ExpressionType;
 import com.speedment.runtime.compute.internal.expression.ComposedUtil;
 import com.speedment.runtime.compute.internal.expression.MapperUtil;
+import com.speedment.runtime.compute.trait.HasCase;
 import com.speedment.runtime.compute.trait.HasCompare;
 import com.speedment.runtime.compute.trait.HasCompose;
 import com.speedment.runtime.compute.trait.HasHash;
@@ -30,6 +31,7 @@ public interface ToString<T>
 extends Expression<T>,
         Function<T, String>,
         HasMap<T, UnaryOperator<String>, ToString<T>>,
+        HasCase<T, ToString<T>>,
         HasHash<T>,
         HasCompare<T>,
         HasCompose<T> {
@@ -66,10 +68,12 @@ default ToString<T> map(UnaryOperator<String> mapper) {
         return MapperUtil.map(this, mapper);
     }
 
+    @Override
     default ToString<T> toUpperCase() {
         return map(String::toUpperCase);
     }
 
+    @Override
     default ToString<T> toLowerCase() {
         return map(String::toLowerCase);
     }
diff --git a/runtime-parent/runtime-compute/src/main/java/com/speedment/runtime/compute/trait/HasCase.java b/runtime-parent/runtime-compute/src/main/java/com/speedment/runtime/compute/trait/HasCase.java
new file mode 100644
index 0000000000..61a6b3c940
--- /dev/null
+++ b/runtime-parent/runtime-compute/src/main/java/com/speedment/runtime/compute/trait/HasCase.java
@@ -0,0 +1,30 @@
+package com.speedment.runtime.compute.trait;
+
+import com.speedment.runtime.compute.expression.Expression;
+
+/**
+ * Trait for expressions that has {@link #toUpperCase()} and
+ * {@link #toLowerCase()} operations.
+ *
+ * @author Emil Forslund
+ * @since  3.1.0
+ */
+public interface HasCase<T, RESULT extends Expression<T>> {
+
+    /**
+     * Returns an expression that is equivalent to this expression, except that
+     * results are always in upper-case letters.
+     *
+     * @return  the upper case expression
+     */
+    RESULT toUpperCase();
+
+    /**
+     * Returns an expression that is equivalent to this expression, except that
+     * results are always in lower-case letters.
+     *
+     * @return  the lower case expression
+     */
+    RESULT toLowerCase();
+
+}