diff --git a/src/test/java/org/springframework/samples/petclinic/rest/controller/PetRestControllerTests.java b/src/test/java/org/springframework/samples/petclinic/rest/controller/PetRestControllerTests.java
index 06f1b5a997a11bed841976b13288343973580b97..a4bce2b9f7690a684630c6961a73b4829e1090e5 100644
--- a/src/test/java/org/springframework/samples/petclinic/rest/controller/PetRestControllerTests.java
+++ b/src/test/java/org/springframework/samples/petclinic/rest/controller/PetRestControllerTests.java
@@ -241,7 +241,8 @@ class PetRestControllerTests {
         String newPetAsJSON = mapper.writeValueAsString(newPet);
         given(this.clinicService.findPetById(999)).willReturn(null);
         this.mockMvc.perform(post("/api/pets")
-                .content(new String()).accept(MediaType.APPLICATION_JSON_VALUE).contentType(MediaType.APPLICATION_JSON_VALUE))
+                // set empty JSON to force 400 error
+                .content("{}").accept(MediaType.APPLICATION_JSON_VALUE).contentType(MediaType.APPLICATION_JSON_VALUE))
             .andExpect(status().isBadRequest());
     }
 }
diff --git a/src/test/java/org/springframework/samples/petclinic/rest/controller/UserRestControllerTests.java b/src/test/java/org/springframework/samples/petclinic/rest/controller/UserRestControllerTests.java
index 9c5f504d6f63dfc3c892f43d7836ae955df725f5..ed65ee184000495c9f8272dd7ab49caced647061 100644
--- a/src/test/java/org/springframework/samples/petclinic/rest/controller/UserRestControllerTests.java
+++ b/src/test/java/org/springframework/samples/petclinic/rest/controller/UserRestControllerTests.java
@@ -63,7 +63,7 @@ class UserRestControllerTests {
     @WithMockUser(roles = "ADMIN")
     void testCreateUserError() throws Exception {
         User user = new User();
-        user.setUsername("username");
+        user.setUsername(""); // set empty username to force 400 error
         user.setPassword("password");
         user.setEnabled(true);
         ObjectMapper mapper = new ObjectMapper();