diff --git a/build.gradle b/build.gradle
index 72050b4..42f2f87 100644
--- a/build.gradle
+++ b/build.gradle
@@ -40,6 +40,6 @@ test {
         showStackTraces true
 
         // Change to `true` for more verbose test output
-        showStandardStreams = false
+        showStandardStreams = true
     }
 }
\ No newline at end of file
diff --git a/src/main/java/djmil/cashcard/CashCardController.java b/src/main/java/djmil/cashcard/CashCardController.java
index 6787d20..f43de99 100644
--- a/src/main/java/djmil/cashcard/CashCardController.java
+++ b/src/main/java/djmil/cashcard/CashCardController.java
@@ -7,6 +7,7 @@ import org.springframework.data.domain.Sort;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RequestMapping;
@@ -74,4 +75,17 @@ public class CashCardController {
 
         return ResponseEntity.created(locationOfNewCashCard).build();
     }
-}
+
+    @PutMapping("/{requestedId}")
+    private ResponseEntity<Void> putCashCard(@PathVariable Long requestedId, @RequestBody CashCard cashCardUpdate, Principal principal) {
+        CashCard cashCard = cashCardRepository.findByIdAndOwner(requestedId, principal.getName());
+
+        if (cashCard == null) {
+            return ResponseEntity.notFound().build();
+        }
+        
+        CashCard updatedCashCard = new CashCard(cashCard.id(), cashCardUpdate.amount(), principal.getName());
+        cashCardRepository.save(updatedCashCard);
+        return ResponseEntity.noContent().build();
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/djmil/cashcard/CashcardApplicationTests.java b/src/test/java/djmil/cashcard/CashcardApplicationTests.java
index a287d48..9dbbc9d 100644
--- a/src/test/java/djmil/cashcard/CashcardApplicationTests.java
+++ b/src/test/java/djmil/cashcard/CashcardApplicationTests.java
@@ -5,6 +5,8 @@ import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.test.annotation.DirtiesContext;
@@ -169,4 +171,37 @@ class CashcardApplicationTests {
 		.getForEntity("/cashcards/102", String.class); // <<-- kumar2's data
 		assertThat(response.getStatusCode()).isEqualTo(HttpStatus.NOT_FOUND);
 	}
+
+	@Test
+	@DirtiesContext
+	void shouldUpdateAnExistingCashCard() {
+		CashCard cashCardUpdate = new CashCard(null, 19.99, null);
+		HttpEntity<CashCard> request = new HttpEntity<>(cashCardUpdate);
+		ResponseEntity<Void> response = restTemplate
+				.withBasicAuth("sarah1", "abc123")
+				.exchange("/cashcards/99", HttpMethod.PUT, request, Void.class);
+		assertThat(response.getStatusCode()).isEqualTo(HttpStatus.NO_CONTENT);
+
+		// Validte that the resource was updated
+		ResponseEntity<String> getResponse = restTemplate
+          		.withBasicAuth("sarah1", "abc123")
+          		.getForEntity("/cashcards/99", String.class);
+  		assertThat(getResponse.getStatusCode()).isEqualTo(HttpStatus.OK);
+
+		DocumentContext documentContext = JsonPath.parse(getResponse.getBody());
+		Number id = documentContext.read("$.id");
+		Double amount = documentContext.read("$.amount");
+		assertThat(id).isEqualTo(99);
+		assertThat(amount).isEqualTo(19.99);
+	}
+
+	@Test
+	void shouldNotUpdateACashCardThatDoesNotExist() {
+		CashCard unknownCard = new CashCard(null, 19.99, null);
+		HttpEntity<CashCard> request = new HttpEntity<>(unknownCard);
+		ResponseEntity<Void> response = restTemplate
+				.withBasicAuth("sarah1", "abc123")
+				.exchange("/cashcards/99999", HttpMethod.PUT, request, Void.class);
+		assertThat(response.getStatusCode()).isEqualTo(HttpStatus.NOT_FOUND);
+	}
 }