diff --git a/.eslintrc.js b/.eslintrc.js
index a6e7c847..f82a6194 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -177,7 +177,7 @@ module.exports = {
 		"no-octal-escape": "error",
 		"no-param-reassign": "off",
 		"no-path-concat": "error",
-		"no-plusplus": ["warn", { "allowForLoopAfterthoughts": true }],
+		"no-plusplus": ["error", { "allowForLoopAfterthoughts": true }],
 		"no-process-env": "error",
 		"no-process-exit": "warn",
 		"no-proto": "error",
diff --git a/packages/lib/factorio/patch.js b/packages/lib/factorio/patch.js
index 7e9fbec6..6b70b1d2 100644
--- a/packages/lib/factorio/patch.js
+++ b/packages/lib/factorio/patch.js
@@ -152,7 +152,7 @@ function reorderDependencies(modules) {
 
 		// No unmet dependencies, record and continue
 		present.set(module.name, module.version);
-		index++;
+		index += 1;
 
 		if (hold.has(module.name)) {
 			modules.splice(index, 0, ...hold.get(module.name));
diff --git a/packages/lib/link/connectors.js b/packages/lib/link/connectors.js
index 37f9c05e..a8d494c9 100644
--- a/packages/lib/link/connectors.js
+++ b/packages/lib/link/connectors.js
@@ -34,7 +34,7 @@ class WebSocketBaseConnector extends events.EventEmitter {
 		let dropCount = 0;
 		for (let index = 0; index < this._sendBuffer.length; index++) {
 			if (this._sendBuffer[index].seq <= seq) {
-				dropCount++;
+				dropCount += 1;
 			} else {
 				break;
 			}
@@ -102,12 +102,14 @@ class WebSocketBaseConnector extends events.EventEmitter {
 		if (!["handshake", "connected", "closing"].includes(this._state)) {
 			throw new libErrors.SessionLost("No session");
 		}
-		let message = { seq: this._seq, type, data };
+		let seq = this._seq;
+		this._seq += 1;
+		let message = { seq, type, data };
 		this._sendBuffer.push(message);
 		if (["connected", "closing"].includes(this._state)) {
 			this._socket.send(JSON.stringify(message));
 		}
-		return this._seq++;
+		return seq;
 	}
 
 	/**
@@ -450,8 +452,10 @@ class VirtualConnector extends events.EventEmitter {
 	 * @returns {number} the sequence number of the message sent
 	 */
 	send(type, data) {
-		this.other.emit("message", { seq: this._seq, type, data });
-		return this._seq++;
+		let seq = this._seq;
+		this._seq += 1;
+		this.other.emit("message", { seq, type, data });
+		return seq;
 	}
 }
 
diff --git a/packages/master/master.js b/packages/master/master.js
index 6268151a..32827da3 100755
--- a/packages/master/master.js
+++ b/packages/master/master.js
@@ -1429,7 +1429,8 @@ async function handleHandshake(message, socket, req, attachHandler) {
 		return;
 	}
 
-	let sessionId = nextSessionId++;
+	let sessionId = nextSessionId;
+	nextSessionId += 1;
 	let sessionToken = jwt.sign({ aud: masterSession, sid: sessionId }, masterConfig.get("master.auth_secret"));
 	let connector = new WebSocketServerConnector(socket, sessionId);
 	activeConnectors.set(sessionId, connector);
diff --git a/plugins/global_chat/test/plugin.js b/plugins/global_chat/test/plugin.js
index 7576a9b6..f371d360 100644
--- a/plugins/global_chat/test/plugin.js
+++ b/plugins/global_chat/test/plugin.js
@@ -46,7 +46,7 @@ describe("global_chat plugin", function() {
 						instancePlugin.instance.connector.sentMessages = [];
 						await instancePlugin.onOutput(output);
 						assert(instancePlugin.instance.connector.sentMessages.length, "message was not sent");
-						count++;
+						count += 1;
 					}
 				}
 				assert(count > 0, "no lines were tested");
@@ -58,7 +58,7 @@ describe("global_chat plugin", function() {
 						instancePlugin.instance.connector.sentMessages = [];
 						await instancePlugin.onOutput(output);
 						assert(!instancePlugin.instance.connector.sentMessages.length, "message was sent");
-						count++;
+						count += 1;
 					}
 				}
 				assert(count > 0, "no lines were tested");
diff --git a/test/integration/export.js b/test/integration/export.js
index c7dc20f8..dccfbb10 100644
--- a/test/integration/export.js
+++ b/test/integration/export.js
@@ -24,7 +24,7 @@ describe("Integration of lib/factorio/export", function() {
 
 				// Value is always a string, nearly always truthy
 				if (!value) {
-					empty_keys++;
+					empty_keys += 1;
 				}
 				assert.equal(typeof value, "string");
 			}
diff --git a/test/lib/factorio/patch.js b/test/lib/factorio/patch.js
index d5d1bdfb..00850590 100644
--- a/test/lib/factorio/patch.js
+++ b/test/lib/factorio/patch.js
@@ -199,7 +199,7 @@ describe("lib/factorio", function() {
 				} catch (err) { }
 				if (success) {
 					validate(modules);
-					successCount++;
+					successCount += 1;
 				}
 			}
 
diff --git a/test/mock.js b/test/mock.js
index 9b9f6cdb..c8cddfbb 100644
--- a/test/mock.js
+++ b/test/mock.js
@@ -58,10 +58,12 @@ class MockConnector extends events.EventEmitter {
 	}
 
 	send(type, data) {
-		let message = { seq: this._seq, type, data };
+		let seq = this._seq;
+		this._seq += 1;
+		let message = { seq, type, data };
 		this.sentMessages.push(message);
 		setImmediate(() => this.emit("send", message));
-		return this._seq++;
+		return seq;
 	}
 }