diff --git a/security/certverifier/CertVerifier.cpp b/security/certverifier/CertVerifier.cpp
--- a/security/certverifier/CertVerifier.cpp
+++ b/security/certverifier/CertVerifier.cpp
@@ -120,16 +120,20 @@ IsCertChainRootBuiltInRoot(const UniqueC
   }
   CERTCertificate* root = rootNode->cert;
   if (!root) {
     return Result::FATAL_ERROR_LIBRARY_FAILURE;
   }
   return IsCertBuiltInRoot(root, result);
 }
 
+// The term "builtin root" traditionally refers to a root CA certificate that
+// has been added to the NSS trust store, because it has been approved
+// for inclusion according to the Mozilla CA policy, and might be accepted
+// by Mozilla applications as an issuer for certificates seen on the public web.
 Result
 IsCertBuiltInRoot(CERTCertificate* cert, bool& result)
 {
   result = false;
 #ifdef DEBUG
   nsCOMPtr<nsINSSComponent> component(do_GetService(PSM_COMPONENT_CONTRACTID));
   if (!component) {
     return Result::FATAL_ERROR_LIBRARY_FAILURE;
@@ -142,25 +146,38 @@ IsCertBuiltInRoot(CERTCertificate* cert,
     return Success;
   }
 #endif // DEBUG
   AutoSECMODListReadLock lock;
   for (SECMODModuleList* list = SECMOD_GetDefaultModuleList(); list;
        list = list->next) {
     for (int i = 0; i < list->module->slotCount; i++) {
       PK11SlotInfo* slot = list->module->slots[i];
-      // PK11_HasRootCerts should return true if and only if the given slot has
-      // an object with a CKA_CLASS of CKO_NETSCAPE_BUILTIN_ROOT_LIST, which
-      // should be true only of the builtin root list.
-      // If we can find a copy of the given certificate on the slot with the
-      // builtin root list, that certificate must be a builtin.
-      if (PK11_IsPresent(slot) && PK11_HasRootCerts(slot) &&
-          PK11_FindCertInSlot(slot, cert, nullptr) != CK_INVALID_HANDLE) {
-        result = true;
-        return Success;
+      // We're searching for the "builtin root module", which is a module that
+      // contains an object with a CKA_CLASS of CKO_NETSCAPE_BUILTIN_ROOT_LIST.
+      // We use PK11_HasRootCerts() to identify a module with that property.
+      // In the past, we exclusively used the PKCS#11 module named nssckbi,
+      // which is provided by the NSS library.
+      // Nowadays, some distributions use a replacement module, which contains
+      // the builtin roots, but which also contains additional CA certificates,
+      // such as CAs trusted in a local deployment.
+      // We want to be able to distinguish between these two categories,
+      // because a CA, which may issue certificates for the public web,
+      // is expected to comply with additional requirements.
+      // If the certificate has attribute CKA_NSS_MOZILLA_CA_POLICY set to true,
+      // then we treat it as a "builtin root".
+      if (PK11_IsPresent(slot) && PK11_HasRootCerts(slot)) {
+        CK_OBJECT_HANDLE handle = PK11_FindCertInSlot(slot, cert, nullptr);
+        if (handle != CK_INVALID_HANDLE &&
+            PK11_HasAttributeSet(slot, handle, CKA_NSS_MOZILLA_CA_POLICY,
+                                 false)) {
+          // Attribute was found, and is set to true
+          result = true;
+          break;
+        }
       }
     }
   }
   return Success;
 }
 
 static Result
 BuildCertChainForOneKeyUsage(NSSCertDBTrustDomain& trustDomain, Input certDER,