diff --git a/engine/src/main/java/pro/verron/officestamper/api/OfficeStamperConfiguration.java b/engine/src/main/java/pro/verron/officestamper/api/OfficeStamperConfiguration.java
index b3b2dc31..e2a7c05f 100644
--- a/engine/src/main/java/pro/verron/officestamper/api/OfficeStamperConfiguration.java
+++ b/engine/src/main/java/pro/verron/officestamper/api/OfficeStamperConfiguration.java
@@ -8,6 +8,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.function.Function;
+import java.util.function.Supplier;
 
 
 /**
@@ -25,8 +26,7 @@ public interface OfficeStamperConfiguration {
      * allows you to define how unresolved expressions are handled in a more flexible and
      * comprehensive manner.
      */
-    @Deprecated(since = "2.5", forRemoval = true)
-    boolean isFailOnUnresolvedExpression();
+    @Deprecated(since = "2.5", forRemoval = true) boolean isFailOnUnresolvedExpression();
 
     /**
      * Sets the failOnUnresolvedExpression flag to determine whether unresolved expressions should
@@ -113,8 +113,7 @@ public interface OfficeStamperConfiguration {
      * allows you to define how unresolved expressions are handled in a more flexible and
      * comprehensive manner.
      */
-    @Deprecated(since = "2.5", forRemoval = true)
-    OfficeStamperConfiguration replaceUnresolvedExpressions(
+    @Deprecated(since = "2.5", forRemoval = true) OfficeStamperConfiguration replaceUnresolvedExpressions(
             boolean replaceUnresolvedExpressions
     );
 
@@ -275,14 +274,13 @@ OfficeStamperConfiguration setSpelParserConfiguration(
 
     List<CustomFunction> customFunctions();
 
+    void addCustomFunction(String name, Supplier<?> implementation);
+
     <T> NeedsFunctionImpl<T> addCustomFunction(String name, Class<T> class0);
 
     <T, U> NeedsBiFunctionImpl<T, U> addCustomFunction(String name, Class<T> class0, Class<U> class1);
 
     <T, U, V> NeedsTriFunctionImpl<T, U, V> addCustomFunction(
-            String name,
-            Class<T> class0,
-            Class<U> class1,
-            Class<V> class2
+            String name, Class<T> class0, Class<U> class1, Class<V> class2
     );
 }
diff --git a/engine/src/main/java/pro/verron/officestamper/core/DocxStamperConfiguration.java b/engine/src/main/java/pro/verron/officestamper/core/DocxStamperConfiguration.java
index f2c7bbf8..8b3944bd 100644
--- a/engine/src/main/java/pro/verron/officestamper/core/DocxStamperConfiguration.java
+++ b/engine/src/main/java/pro/verron/officestamper/core/DocxStamperConfiguration.java
@@ -20,6 +20,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.function.Function;
+import java.util.function.Supplier;
 
 /**
  * The {@link DocxStamperConfiguration} class represents the configuration for
@@ -403,6 +404,11 @@ public void addCustomFunction(CustomFunction function) {
     }
 
 
+    @Override public void addCustomFunction(String name, Supplier<?> implementation) {
+        this.addCustomFunction(new CustomFunction(name, List.of(), args -> implementation.get()));
+    }
+
+
     @Override public <T> NeedsFunctionImpl<T> addCustomFunction(String name, Class<T> class0) {
         return new FunctionBuilder<>(this, name, class0);
     }
diff --git a/engine/src/test/java/pro/verron/officestamper/test/Contexts.java b/engine/src/test/java/pro/verron/officestamper/test/Contexts.java
index c2b78a6e..c078a701 100644
--- a/engine/src/test/java/pro/verron/officestamper/test/Contexts.java
+++ b/engine/src/test/java/pro/verron/officestamper/test/Contexts.java
@@ -7,6 +7,7 @@
 import pro.verron.officestamper.preset.StampTable;
 
 import java.nio.file.Path;
+import java.time.LocalDate;
 import java.util.*;
 
 import static org.junit.jupiter.params.provider.Arguments.of;
@@ -192,18 +193,6 @@ public static Map<String, Object> coupleContext() {
         return context;
     }
 
-    /**
-     * <p>nowContext.</p>
-     *
-     * @return a {@link Contexts.DateContext} object
-     *
-     * @since 1.6.6
-     */
-    public static DateContext nowContext() {
-        var now = new Date();
-        return new DateContext(now);
-    }
-
     /**
      * <p>mapAndReflectiveContext.</p>
      *
@@ -285,13 +274,6 @@ public record Role(String name, String actor) {}
      */
     public record Characters(List<Role> characters) {}
 
-    /**
-     * Represents a Date context.
-     *
-     * @param date The Date value to be encapsulated in the context.
-     */
-    public record DateContext(Date date) {}
-
     public record ZonedDateContext(java.time.ZonedDateTime date) {}
 
     /**
@@ -614,4 +596,8 @@ public record Name(String name) {}
     public static class EmptyContext {}
 
     public record TableContext(StampTable characters) {}
+
+    public record DateContext(LocalDate date) {
+
+    }
 }
diff --git a/engine/src/test/java/pro/verron/officestamper/test/CustomFunctionTests.java b/engine/src/test/java/pro/verron/officestamper/test/CustomFunctionTests.java
index 1951b5bc..d2ce6eb4 100644
--- a/engine/src/test/java/pro/verron/officestamper/test/CustomFunctionTests.java
+++ b/engine/src/test/java/pro/verron/officestamper/test/CustomFunctionTests.java
@@ -1,24 +1,31 @@
 package pro.verron.officestamper.test;
 
+import org.docx4j.openpackaging.exceptions.Docx4JException;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
 import pro.verron.officestamper.test.Functions.UppercaseFunction;
 
+import java.io.IOException;
+import java.math.BigDecimal;
 import java.nio.file.Path;
+import java.time.LocalDate;
+import java.time.Month;
+import java.time.format.DateTimeFormatter;
+import java.util.List;
+import java.util.Locale;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static pro.verron.officestamper.preset.OfficeStamperConfigurations.standard;
 import static pro.verron.officestamper.test.TestUtils.getResource;
+import static pro.verron.officestamper.test.TestUtils.makeResource;
 
-@DisplayName("Custom functions")
-class CustomFunctionTests {
+@DisplayName("Custom functions") class CustomFunctionTests {
 
 
-    @DisplayName("Should works with variables, multiline text, in comment content, inside comment, and in repetitions.")
-    @Test()
-    void features() {
-        var config = standard()
-                .exposeInterfaceToExpressionLanguage(UppercaseFunction.class, Functions.upperCase());
+    @DisplayName("Should allow to inject full interfaces") @Test() void interfaces() {
+        var config = standard().exposeInterfaceToExpressionLanguage(UppercaseFunction.class, Functions.upperCase());
         var template = getResource(Path.of("CustomExpressionFunction.docx"));
         var context = Contexts.show();
         var stamper = new TestDocxStamper<>(config);
@@ -60,4 +67,66 @@ void features() {
         var actual = stamper.stampAndLoadAndExtract(template, context);
         assertEquals(expected, actual);
     }
+
+    @DisplayName("Should allow to inject lambda functions") @Test() void functions()
+            throws IOException, Docx4JException {
+        var config = standard();
+        config.addCustomFunction("toUppercase", String.class)
+              .withImplementation(String::toUpperCase);
+        var template = makeResource("${toUppercase(name)}");
+        var context = Contexts.show();
+        var stamper = new TestDocxStamper<>(config);
+        var expected = """
+                THE SIMPSONS
+                """;
+        var actual = stamper.stampAndLoadAndExtract(template, context);
+        assertEquals(expected, actual);
+    }
+
+    @DisplayName("Should allow to inject lambda suppliers.") @Test() void suppliers()
+            throws IOException, Docx4JException {
+        var config = standard();
+        config.addCustomFunction("foo", () -> List.of("a", "b", "c"));
+        var template = makeResource("${foo()}");
+        var context = Contexts.empty();
+        var stamper = new TestDocxStamper<>(config);
+        var expected = """
+                [a, b, c]
+                """;
+        var actual = stamper.stampAndLoadAndExtract(template, context);
+        assertEquals(expected, actual);
+    }
+
+    @DisplayName("Should allow to inject lambda suppliers.") @Test() void bifunctions()
+            throws IOException, Docx4JException {
+        var config = standard();
+        config.addCustomFunction("Add", String.class, Integer.class)
+              .withImplementation((s, i) -> new BigDecimal(s).add(new BigDecimal(i)));
+        var template = makeResource("${Add('3.22', 4)}");
+        var context = Contexts.empty();
+        var stamper = new TestDocxStamper<>(config);
+        var expected = """
+                7.22
+                """;
+        var actual = stamper.stampAndLoadAndExtract(template, context);
+        assertEquals(expected, actual);
+    }
+
+    @DisplayName("Should allow to inject lambda trifunctions.")
+    @CsvSource({"ZH,2024 四月", "FR,2024 avril", "EN,2024 April", "JA,2024 4月", "HE,2024 אפריל", "IT,2024 aprile"})
+    @ParameterizedTest() void trifunctions(String tag, String expected)
+            throws IOException, Docx4JException {
+        var config = standard();
+        config.addCustomFunction("format", LocalDate.class, String.class, String.class)
+              .withImplementation((date, pattern, languageTag) -> {
+                  var locale = Locale.forLanguageTag(languageTag);
+                  var formatter = DateTimeFormatter.ofPattern(pattern, locale);
+                  return formatter.format(date);
+              });
+        var template = makeResource("${format(date,'yyyy MMMM','%s')}" .formatted(tag));
+        var context = new Contexts.DateContext(LocalDate.of(2024, Month.APRIL, 1));
+        var stamper = new TestDocxStamper<>(config);
+        var actual = stamper.stampAndLoadAndExtract(template, context);
+        assertEquals(expected + "\n", actual);
+    }
 }