diff --git a/lib/core/sdam/topology_description.js b/lib/core/sdam/topology_description.js
index ba6a2507ee..d1beb22c7c 100644
--- a/lib/core/sdam/topology_description.js
+++ b/lib/core/sdam/topology_description.js
@@ -279,6 +279,26 @@ function topologyTypeForServerType(serverType) {
   return TopologyType.ReplicaSetNoPrimary;
 }
 
+function compareObjectId(oid1, oid2) {
+  if (oid1 == null) {
+    return -1;
+  }
+
+  if (oid2 == null) {
+    return 1;
+  }
+
+  if (oid1.id instanceof Buffer && oid2.id instanceof Buffer) {
+    const oid1Buffer = oid1.id;
+    const oid2Buffer = oid2.id;
+    return oid1Buffer.compare(oid2Buffer);
+  }
+
+  const oid1String = oid1.toString();
+  const oid2String = oid2.toString();
+  return oid1String.localeCompare(oid2String);
+}
+
 function updateRsFromPrimary(
   serverDescriptions,
   setName,
@@ -292,11 +312,13 @@ function updateRsFromPrimary(
     return [checkHasPrimary(serverDescriptions), setName, maxSetVersion, maxElectionId];
   }
 
-  const electionIdOID = serverDescription.electionId ? serverDescription.electionId.$oid : null;
-  const maxElectionIdOID = maxElectionId ? maxElectionId.$oid : null;
-  if (serverDescription.setVersion != null && electionIdOID != null) {
-    if (maxSetVersion != null && maxElectionIdOID != null) {
-      if (maxSetVersion > serverDescription.setVersion || maxElectionIdOID > electionIdOID) {
+  const electionId = serverDescription.electionId ? serverDescription.electionId : null;
+  if (serverDescription.setVersion && electionId) {
+    if (maxSetVersion && maxElectionId) {
+      if (
+        maxSetVersion > serverDescription.setVersion ||
+        compareObjectId(maxElectionId, electionId) > 0
+      ) {
         // this primary is stale, we must remove it
         serverDescriptions.set(
           serverDescription.address,
diff --git a/test/unit/core/sdam_spec.test.js b/test/unit/core/sdam_spec.test.js
index a22b5d3756..8d8eaa3f70 100644
--- a/test/unit/core/sdam_spec.test.js
+++ b/test/unit/core/sdam_spec.test.js
@@ -7,6 +7,7 @@ const ServerDescription = require('../../../lib/core/sdam/server_description').S
 const sdamEvents = require('../../../lib/core/sdam/events');
 const parse = require('../../../lib/core/uri_parser');
 const sinon = require('sinon');
+const EJSON = require('mongodb-extjson');
 
 const chai = require('chai');
 chai.use(require('chai-subset'));
@@ -25,7 +26,10 @@ function collectTests() {
       .readdirSync(path.join(specDir, testType))
       .filter(f => path.extname(f) === '.json')
       .map(f => {
-        const result = JSON.parse(fs.readFileSync(path.join(specDir, testType, f)));
+        const result = EJSON.parse(fs.readFileSync(path.join(specDir, testType, f)), {
+          relaxed: true
+        });
+
         result.type = testType;
         return result;
       });
@@ -226,7 +230,7 @@ function executeSDAMTest(testData, testDone) {
               const omittedFields = findOmittedFields(expectedServer);
 
               const actualServer = actualServers.get(serverName);
-              expect(actualServer).to.deep.include(expectedServer);
+              expect(actualServer).to.matchMongoSpec(expectedServer);
 
               if (omittedFields.length) {
                 expect(actualServer).to.not.have.all.keys(omittedFields);
@@ -254,7 +258,7 @@ function executeSDAMTest(testData, testDone) {
           }
 
           expect(description).to.include.keys(translatedKey);
-          expect(description[translatedKey]).to.eql(outcomeValue);
+          expect(description[translatedKey]).to.eql(outcomeValue, `(key="${translatedKey}")`);
         });
 
         // remove error handler