diff --git a/src/NuGetGallery/Controllers/ApiController.cs b/src/NuGetGallery/Controllers/ApiController.cs
index ef4ffc6538..b16000ba0c 100644
--- a/src/NuGetGallery/Controllers/ApiController.cs
+++ b/src/NuGetGallery/Controllers/ApiController.cs
@@ -289,9 +289,10 @@ await AuditingService.SaveAuditRecord(
                                         attemptedPackage: new AuditedPackageIdentifier(
                                             nuspec.GetId(), nuspec.GetVersion().ToNormalizedStringSafe())));
 
-                                // User can not push this package
-                                return new HttpStatusCodeWithBodyResult(HttpStatusCode.Forbidden,
-                                    Strings.ApiKeyNotAuthorized);
+                                // User cannot push a package to an ID owned by another user.
+                                return new HttpStatusCodeWithBodyResult(HttpStatusCode.Conflict,
+                                    String.Format(CultureInfo.CurrentCulture, Strings.PackageIdNotAvailable,
+                                        nuspec.GetId()));
                             }
 
                             // Check if a particular Id-Version combination already exists. We eventually need to remove this check.
diff --git a/tests/NuGetGallery.Facts/Controllers/ApiControllerFacts.cs b/tests/NuGetGallery.Facts/Controllers/ApiControllerFacts.cs
index b9d8ef1896..b881772fc1 100644
--- a/tests/NuGetGallery.Facts/Controllers/ApiControllerFacts.cs
+++ b/tests/NuGetGallery.Facts/Controllers/ApiControllerFacts.cs
@@ -261,6 +261,38 @@ public async Task WillReturnConflictIfAPackageWithTheIdAndSameNormalizedVersionA
                     String.Format(Strings.PackageExistsAndCannotBeModified, "theId", "1.0.42"));
             }
 
+            [Fact]
+            public async Task WillReturnConflictIfAPackageWithTheIdExistsBelongingToAnotherUser()
+            {
+                // Arrange
+                var user = new User { EmailAddress = "confirmed@email.com" };
+                var packageId = "theId";
+                var packageRegistration = new PackageRegistration();
+                packageRegistration.Id = packageId;
+                var package = new Package();
+                package.PackageRegistration = packageRegistration;
+                package.Version = "1.0.42";
+                packageRegistration.Packages.Add(package);
+
+                var controller = new TestableApiController();
+                controller.SetCurrentUser(user);
+                controller.MockPackageService.Setup(p => p.FindPackageRegistrationById(It.IsAny<string>()))
+                    .Returns(packageRegistration);
+
+                var nuGetPackage = TestPackage.CreateTestPackageStream(packageId, "1.0.42");
+                controller.SetCurrentUser(new User());
+                controller.SetupPackageFromInputStream(nuGetPackage);
+
+                // Act
+                var result = await controller.CreatePackagePut();
+
+                // Assert
+                ResultAssert.IsStatusCode(
+                    result,
+                    HttpStatusCode.Conflict,
+                    String.Format(Strings.PackageIdNotAvailable, packageId));
+            }
+
             [Fact]
             public void WillCreateAPackageFromTheNuGetPackage()
             {