diff --git a/package.json b/package.json
index dc24c71..e480ea3 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "@subsquid/cli",
   "description": "squid cli tool",
-  "version": "3.3.3",
+  "version": "3.3.4",
   "license": "GPL-3.0-or-later",
   "repository": {
     "type": "git",
@@ -81,7 +81,7 @@
     "@oclif/plugin-autocomplete": "3.2.2",
     "@oclif/plugin-warn-if-update-available": "^3.1.13",
     "@subsquid/commands": "^2.3.1",
-    "@subsquid/manifest": "^2.1.2",
+    "@subsquid/manifest": "^2.1.3",
     "@types/fast-levenshtein": "^0.0.4",
     "@types/lodash": "^4.17.7",
     "@types/targz": "^1.0.4",
diff --git a/src/commands/deploy.ts b/src/commands/deploy.ts
index b55006a..c12f3b2 100644
--- a/src/commands/deploy.ts
+++ b/src/commands/deploy.ts
@@ -3,7 +3,7 @@ import path from 'node:path';
 import { promisify } from 'util';
 
 import { Args, Flags, ux as CliUx } from '@oclif/core';
-import { Manifest } from '@subsquid/manifest';
+import { Manifest, ManifestValue } from '@subsquid/manifest';
 import chalk from 'chalk';
 import diff from 'cli-diff';
 import { globSync } from 'glob';
@@ -258,6 +258,17 @@ export default class Deploy extends DeployCommand {
       if (!update) return;
     }
 
+    /**
+     * Prevent deploying if the Postgres version has changed (requires hard reset)
+     */
+    const versionMismatch = getPostgresVersionMismatch(target, manifest);
+    if (!hardReset && versionMismatch) {
+      this.error(
+        `The squid ${printSquid(target!)} is currently using Postgres ${versionMismatch.currentVersion}, but the new manifest specifies Postgres ${versionMismatch.newVersion}. ` +
+          `Changing the Postgres version requires a hard reset. Please do it explicitly using "--hard-reset" flag.`,
+      );
+    }
+
     /**
      * Warn if the existing squid has a Postgres addon but the new manifest removes it
      */
@@ -545,3 +556,20 @@ export function getIgnorePatterns(ignoreDir: string, raw: string) {
 function toRootPattern(pattern: string) {
   return pattern.startsWith('/') ? pattern : `/${pattern}`;
 }
+
+export function getPostgresVersionMismatch(
+  target: Squid | null,
+  manifest: Manifest,
+): { currentVersion: string; newVersion: string } | null {
+  if (!target?.addons?.postgres || !manifest.deploy?.addons?.postgres) return null;
+
+  const currentManifest = target.manifest.current as ManifestValue;
+  const currentVersion = currentManifest.deploy?.addons?.postgres?.version;
+  const newVersion = manifest.deploy.addons.postgres.version;
+
+  if (currentVersion && newVersion && currentVersion !== newVersion) {
+    return { currentVersion, newVersion };
+  }
+
+  return null;
+}
diff --git a/src/commands/deploy.unit.spec.ts b/src/commands/deploy.unit.spec.ts
index 843b38f..9e9c11b 100644
--- a/src/commands/deploy.unit.spec.ts
+++ b/src/commands/deploy.unit.spec.ts
@@ -1,4 +1,4 @@
-import { getIgnorePatterns } from './deploy';
+import { getIgnorePatterns, getPostgresVersionMismatch } from './deploy';
 
 describe('Deploy', () => {
   describe('get squid ignore paths', () => {
@@ -25,4 +25,58 @@ describe('Deploy', () => {
       expect(patterns).toEqual(['/dir/.git', '/dir/builds', '/dir/abi', '/dir/**/test', '/dir/**/.env', '/dir/**/foo']);
     });
   });
+
+  describe('getPostgresVersionMismatch', () => {
+    function makeTarget(pgVersion?: string) {
+      return {
+        addons: pgVersion
+          ? { postgres: { connections: [], disk: { usageStatus: 'NORMAL', usedBytes: 0, totalBytes: 0 } } }
+          : undefined,
+        manifest: {
+          current: pgVersion
+            ? { deploy: { addons: { postgres: { version: pgVersion } } } }
+            : { deploy: {} },
+          raw: '',
+        },
+      } as any;
+    }
+
+    function makeManifest(pgVersion?: string) {
+      return {
+        deploy: pgVersion ? { addons: { postgres: { version: pgVersion } } } : { addons: {} },
+      } as any;
+    }
+
+    it('returns mismatch when versions differ', () => {
+      const result = getPostgresVersionMismatch(makeTarget('16'), makeManifest('17'));
+      expect(result).toEqual({ currentVersion: '16', newVersion: '17' });
+    });
+
+    it('returns null when versions match', () => {
+      const result = getPostgresVersionMismatch(makeTarget('16'), makeManifest('16'));
+      expect(result).toBeNull();
+    });
+
+    it('returns null when target is null', () => {
+      const result = getPostgresVersionMismatch(null, makeManifest('17'));
+      expect(result).toBeNull();
+    });
+
+    it('returns null when target has no postgres addon', () => {
+      const result = getPostgresVersionMismatch(makeTarget(), makeManifest('17'));
+      expect(result).toBeNull();
+    });
+
+    it('returns null when new manifest has no postgres addon', () => {
+      const result = getPostgresVersionMismatch(makeTarget('16'), makeManifest());
+      expect(result).toBeNull();
+    });
+
+    it('returns null when current manifest has no postgres version', () => {
+      const target = makeTarget('16');
+      target.manifest.current = { deploy: { addons: { postgres: {} } } };
+      const result = getPostgresVersionMismatch(target, makeManifest('17'));
+      expect(result).toBeNull();
+    });
+  });
 });
diff --git a/yarn.lock b/yarn.lock
index 76de593..6a0f07e 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1411,7 +1411,7 @@ __metadata:
     "@oclif/plugin-autocomplete": "npm:3.2.2"
     "@oclif/plugin-warn-if-update-available": "npm:^3.1.13"
     "@subsquid/commands": "npm:^2.3.1"
-    "@subsquid/manifest": "npm:^2.1.2"
+    "@subsquid/manifest": "npm:^2.1.3"
     "@types/async-retry": "npm:^1.4.8"
     "@types/blessed": "npm:^0.1.25"
     "@types/cross-spawn": "npm:^6.0.6"
@@ -1505,14 +1505,14 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@subsquid/manifest@npm:^2.1.2":
-  version: 2.1.2
-  resolution: "@subsquid/manifest@npm:2.1.2"
+"@subsquid/manifest@npm:^2.1.3":
+  version: 2.1.3
+  resolution: "@subsquid/manifest@npm:2.1.3"
   dependencies:
     joi: "npm:17.13.3"
     js-yaml: "npm:^4.1.0"
     lodash: "npm:^4.17.21"
-  checksum: 10c0/20282d0e6278a4df28313fb4ade39c6a81a11caa49eb43a117e5cb115e731d693797a784080deab4587d4df17da94475c843550cdedf444f0543f32ac338084a
+  checksum: 10c0/ad569035cebd8c4fc6c67f7af7e827cc5a5925186fcb9205c88f28f18257779cb8f456cfbe0ae5ce1d735928cdc530b1b0974ca088a13056b4f4e6bab24f1025
   languageName: node
   linkType: hard