diff --git a/spring-boot/argumentresolver/gradle/wrapper/gradle-wrapper.jar b/spring-boot/argumentresolver/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 0000000..29953ea
Binary files /dev/null and b/spring-boot/argumentresolver/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/spring-boot/argumentresolver/gradle/wrapper/gradle-wrapper.properties b/spring-boot/argumentresolver/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000..9492014
--- /dev/null
+++ b/spring-boot/argumentresolver/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.0.1-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
diff --git a/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/ErrorHandler.java b/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/ErrorHandler.java
index f0b6419..08152e6 100644
--- a/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/ErrorHandler.java
+++ b/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/ErrorHandler.java
@@ -3,13 +3,12 @@ package io.reflectoring.argumentresolver;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.ControllerAdvice;
 import org.springframework.web.bind.annotation.ExceptionHandler;
-import org.springframework.web.client.HttpStatusCodeException;
 
 @ControllerAdvice
 class ErrorHandler {
 
-  @ExceptionHandler(HttpStatusCodeException.class)
-  ResponseEntity<?> handleHttpStatusCodeException(HttpStatusCodeException e) {
+  @ExceptionHandler(NotFoundException.class)
+  ResponseEntity<?> handleHttpStatusCodeException(NotFoundException e) {
     return ResponseEntity.status(e.getStatusCode()).build();
   }
 
diff --git a/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/Repository.java b/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/Repository.java
index f9abb4d..9852896 100644
--- a/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/Repository.java
+++ b/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/Repository.java
@@ -4,7 +4,7 @@ package io.reflectoring.argumentresolver;
 import lombok.Value;
 
 @Value
-public class Repository {
+class Repository {
 
   private final Long id;
   private final String slug;
diff --git a/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/RepositoryArgumentResolver.java b/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/RepositoryArgumentResolver.java
index 331ec5d..67ad9be 100644
--- a/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/RepositoryArgumentResolver.java
+++ b/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/RepositoryArgumentResolver.java
@@ -1,7 +1,6 @@
 package io.reflectoring.argumentresolver;
 
 import java.util.Optional;
-import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import lombok.RequiredArgsConstructor;
 import org.springframework.core.MethodParameter;
@@ -14,8 +13,6 @@ import org.springframework.web.method.support.ModelAndViewContainer;
 @RequiredArgsConstructor
 class RepositoryArgumentResolver implements HandlerMethodArgumentResolver {
 
-  private static final Pattern SLUG_PATTERN = Pattern.compile("^/([^/]*).*$");
-
   private final RepositoryFinder repositoryFinder;
 
   @Override
@@ -32,20 +29,9 @@ class RepositoryArgumentResolver implements HandlerMethodArgumentResolver {
 
     String requestPath = ((ServletWebRequest) webRequest).getRequest().getPathInfo();
 
-    Matcher matcher = SLUG_PATTERN.matcher(requestPath);
-
-    if (!matcher.matches()) {
-      throw new IllegalArgumentException(String.format(
-          "Cannot resolve argument of type Site. Expecting the slug to be the first part of the request path (%s).",
-          requestPath));
-    }
-
-    String slug = matcher.group(1);
-    if (slug == null || slug.isBlank()) {
-      throw new IllegalArgumentException(String.format(
-          "Cannot resolve argument of type Site. Slug is empty (request path: %s).",
-          requestPath));
-    }
+    String slug = requestPath
+        .substring(0, requestPath.indexOf("/", 1))
+        .replaceAll("^/", "");
 
     Optional<Repository> repository = repositoryFinder.findBySlug(slug);
 
diff --git a/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/RepositoryId.java b/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/RepositoryId.java
new file mode 100644
index 0000000..f55ef68
--- /dev/null
+++ b/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/RepositoryId.java
@@ -0,0 +1,10 @@
+package io.reflectoring.argumentresolver;
+
+import lombok.Value;
+
+@Value
+class RepositoryId {
+
+  private final long value;
+
+}
diff --git a/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/RepositoryIdConverter.java b/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/RepositoryIdConverter.java
new file mode 100644
index 0000000..bc054a9
--- /dev/null
+++ b/spring-boot/argumentresolver/src/main/java/io/reflectoring/argumentresolver/RepositoryIdConverter.java
@@ -0,0 +1,13 @@
+package io.reflectoring.argumentresolver;
+
+import org.springframework.core.convert.converter.Converter;
+import org.springframework.stereotype.Component;
+
+@Component
+class RepositoryIdConverter implements Converter<String, RepositoryId> {
+
+  @Override
+  public RepositoryId convert(String source) {
+    return new RepositoryId(Long.parseLong(source));
+  }
+}
diff --git a/spring-boot/argumentresolver/src/test/java/io/reflectoring/argumentresolver/RepositoryArgumentResolverTest.java b/spring-boot/argumentresolver/src/test/java/io/reflectoring/argumentresolver/RepositoryArgumentResolverTest.java
index ce14a4a..74d6fe8 100644
--- a/spring-boot/argumentresolver/src/test/java/io/reflectoring/argumentresolver/RepositoryArgumentResolverTest.java
+++ b/spring-boot/argumentresolver/src/test/java/io/reflectoring/argumentresolver/RepositoryArgumentResolverTest.java
@@ -11,7 +11,7 @@ import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
 import org.springframework.boot.test.mock.mockito.MockBean;
 import org.springframework.test.web.servlet.MockMvc;
 
-@WebMvcTest(controllers = TestController.class)
+@WebMvcTest(controllers = RepositoryArgumentResolverTestController.class)
 class RepositoryArgumentResolverTest {
 
   @Autowired
@@ -26,7 +26,7 @@ class RepositoryArgumentResolverTest {
     given(repositoryFinder.findBySlug("my-repo"))
         .willReturn(Optional.of(new Repository(1L, "my-repo")));
 
-    mockMvc.perform(get("/my-repo/foo"))
+    mockMvc.perform(get("/my-repo/listContributors"))
         .andExpect(status().isOk());
   }
 
@@ -36,7 +36,7 @@ class RepositoryArgumentResolverTest {
     given(repositoryFinder.findBySlug("unknownSlug"))
         .willReturn(Optional.empty());
 
-    mockMvc.perform(get("/unknownSlug/foo"))
+    mockMvc.perform(get("/unknownSlug/listContributors"))
         .andExpect(status().isNotFound());
   }
 
diff --git a/spring-boot/argumentresolver/src/test/java/io/reflectoring/argumentresolver/TestController.java b/spring-boot/argumentresolver/src/test/java/io/reflectoring/argumentresolver/RepositoryArgumentResolverTestController.java
similarity index 56%
rename from spring-boot/argumentresolver/src/test/java/io/reflectoring/argumentresolver/TestController.java
rename to spring-boot/argumentresolver/src/test/java/io/reflectoring/argumentresolver/RepositoryArgumentResolverTestController.java
index 4ed049a..39deda6 100644
--- a/spring-boot/argumentresolver/src/test/java/io/reflectoring/argumentresolver/TestController.java
+++ b/spring-boot/argumentresolver/src/test/java/io/reflectoring/argumentresolver/RepositoryArgumentResolverTestController.java
@@ -3,13 +3,15 @@ package io.reflectoring.argumentresolver;
 import static org.assertj.core.api.Assertions.assertThat;
 
 import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
 
 @RestController
-class TestController {
+@RequestMapping(path = "/{repositorySlug}")
+class RepositoryArgumentResolverTestController {
 
-  @GetMapping("/{slug}/foo")
-  String getSomething(Repository repository) {
+  @GetMapping("/listContributors")
+  String listContributors(Repository repository) {
     assertThat(repository.getId()).isEqualTo(1L);
     return "test";
   }
diff --git a/spring-boot/argumentresolver/src/test/java/io/reflectoring/argumentresolver/RepositoryIdConverterTest.java b/spring-boot/argumentresolver/src/test/java/io/reflectoring/argumentresolver/RepositoryIdConverterTest.java
new file mode 100644
index 0000000..13545ca
--- /dev/null
+++ b/spring-boot/argumentresolver/src/test/java/io/reflectoring/argumentresolver/RepositoryIdConverterTest.java
@@ -0,0 +1,27 @@
+package io.reflectoring.argumentresolver;
+
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
+import org.springframework.boot.test.mock.mockito.MockBean;
+import org.springframework.test.web.servlet.MockMvc;
+
+@WebMvcTest(controllers = RepositoryIdConverterTestController.class)
+class RepositoryIdConverterTest {
+
+  @Autowired
+  private MockMvc mockMvc;
+
+  @MockBean
+  private RepositoryFinder repositoryFinder;
+
+  @Test
+  void resolvesRepositoryId() throws Exception {
+    mockMvc.perform(get("/repositories/42"))
+        .andExpect(status().isOk());
+  }
+
+}
\ No newline at end of file
diff --git a/spring-boot/argumentresolver/src/test/java/io/reflectoring/argumentresolver/RepositoryIdConverterTestController.java b/spring-boot/argumentresolver/src/test/java/io/reflectoring/argumentresolver/RepositoryIdConverterTestController.java
new file mode 100644
index 0000000..fdf7ff8
--- /dev/null
+++ b/spring-boot/argumentresolver/src/test/java/io/reflectoring/argumentresolver/RepositoryIdConverterTestController.java
@@ -0,0 +1,18 @@
+package io.reflectoring.argumentresolver;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+class RepositoryIdConverterTestController {
+
+  @GetMapping("/repositories/{repositoryId}")
+  String getRepository(@PathVariable("repositoryId") RepositoryId repositoryId) {
+    assertThat(repositoryId).isNotNull();
+    return "test";
+  }
+
+}