diff --git a/java/com/google/gerrit/plugins/checks/api/ChecksImpl.java b/java/com/google/gerrit/plugins/checks/api/ChecksImpl.java
index 2a42c5f..361efe0 100644
--- a/java/com/google/gerrit/plugins/checks/api/ChecksImpl.java
+++ b/java/com/google/gerrit/plugins/checks/api/ChecksImpl.java
@@ -71,7 +71,14 @@
       return checkApiImplFactory.create(
           new CheckResource(
               revisionResource,
-              check.orElseThrow(() -> new ResourceNotFoundException("Not found: " + checkerUuid))));
+              check.orElseThrow(
+                  () ->
+                      new ResourceNotFoundException(
+                          String.format(
+                              "Patch set %s in project %s doesn't have check for checker %s.",
+                              revisionResource.getPatchSet().getId(),
+                              revisionResource.getProject(),
+                              checkerUuid)))));
     } catch (Exception e) {
       throw asRestApiException("Cannot parse check", e);
     }
diff --git a/javatests/com/google/gerrit/plugins/checks/acceptance/api/GetCheckIT.java b/javatests/com/google/gerrit/plugins/checks/acceptance/api/GetCheckIT.java
index 2df195b..d16e850 100644
--- a/javatests/com/google/gerrit/plugins/checks/acceptance/api/GetCheckIT.java
+++ b/javatests/com/google/gerrit/plugins/checks/acceptance/api/GetCheckIT.java
@@ -57,7 +57,10 @@
     checkOperations.newCheck(checkKey).setState(CheckState.RUNNING).upsert();
 
     exception.expect(ResourceNotFoundException.class);
-    exception.expectMessage("Not found: " + checkerUuid);
+    exception.expectMessage(
+        String.format(
+            "Patch set %s in project %s doesn't have check for checker %s.",
+            patchSetId, project, checkerUuid));
     checksApiFactory.revision(patchSetId).id(checkerUuid);
   }
 
@@ -73,7 +76,10 @@
     checkerOperations.checker(checkerUuid).forUpdate().disable().update();
 
     exception.expect(ResourceNotFoundException.class);
-    exception.expectMessage("Not found: " + checkerUuid);
+    exception.expectMessage(
+        String.format(
+            "Patch set %s in project %s doesn't have check for checker %s.",
+            patchSetId, project, checkerUuid));
     checksApiFactory.revision(patchSetId).id(checkerUuid);
   }