diff --git a/src/js/core/read_write_proxy.js b/src/js/core/read_write_proxy.js
index c9439603..48e12b4c 100644
--- a/src/js/core/read_write_proxy.js
+++ b/src/js/core/read_write_proxy.js
@@ -2,7 +2,7 @@
 import { Application } from "../application";
 /* typehints:end */
 
-import { sha1, CRC_PREFIX } from "./sensitive_utils.encrypt";
+import { sha1, CRC_PREFIX, computeCrc } from "./sensitive_utils.encrypt";
 import { createLogger } from "./logging";
 import { FILE_NOT_FOUND } from "../platform/storage";
 import { accessNestedPropertyReverse } from "./utils";
@@ -11,7 +11,6 @@ import { ExplainedResult } from "./explained_result";
 import { decompressX64, compressX64 } from "./lzstring";
 import { asyncCompressor, compressionPrefix } from "./async_compression";
 import { compressObject, decompressObject } from "../savegame/savegame_compressor";
-import crc32 from "crc/crc32";
 
 const logger = createLogger("read_write_proxy");
 
@@ -85,7 +84,7 @@ export class ReadWriteProxy {
      */
     static serializeObject(obj) {
         const jsonString = JSON.stringify(compressObject(obj));
-        const checksum = CRC_PREFIX + crc32(jsonString + salt).toString(16);
+        const checksum = computeCrc(jsonString + salt);
         return compressionPrefix + compressX64(checksum + jsonString);
     }
 
@@ -109,7 +108,7 @@ export class ReadWriteProxy {
         const jsonString = decompressed.substr(40);
 
         const desiredChecksum = checksum.startsWith(CRC_PREFIX)
-            ? CRC_PREFIX + crc32(jsonString + salt).toString(16)
+            ? computeCrc(jsonString + salt)
             : sha1(jsonString + salt);
 
         if (desiredChecksum !== checksum) {
@@ -191,12 +190,14 @@ export class ReadWriteProxy {
                         const jsonString = decompressed.substr(40);
 
                         const desiredChecksum = checksum.startsWith(CRC_PREFIX)
-                            ? CRC_PREFIX + crc32(jsonString + salt).toString(16)
+                            ? computeCrc(jsonString + salt)
                             : sha1(jsonString + salt);
 
                         if (desiredChecksum !== checksum) {
                             // Checksum mismatch
-                            return Promise.reject("bad-content / checksum-mismatch");
+                            return Promise.reject(
+                                "bad-content / checksum-mismatch: " + desiredChecksum + " vs " + checksum
+                            );
                         }
                         return jsonString;
                     } else {
diff --git a/src/js/core/sensitive_utils.encrypt.js b/src/js/core/sensitive_utils.encrypt.js
index a35165ef..5a83bf76 100644
--- a/src/js/core/sensitive_utils.encrypt.js
+++ b/src/js/core/sensitive_utils.encrypt.js
@@ -1,5 +1,5 @@
 import { createHash } from "rusha";
-
+import crc32 from "crc/crc32";
 import { decompressX64 } from "./lzstring";
 
 export function sha1(str) {
@@ -13,3 +13,11 @@ export function getNameOfProvider() {
 
 // Distinguish legacy crc prefixes
 export const CRC_PREFIX = "crc32".padEnd(32, "-");
+
+/**
+ * Computes the crc for a given string
+ * @param {string} str
+ */
+export function computeCrc(str) {
+    return CRC_PREFIX + crc32(str).toString(16).padStart(8, "0");
+}
diff --git a/src/js/webworkers/compression.worker.js b/src/js/webworkers/compression.worker.js
index 855d3f50..56581ac1 100644
--- a/src/js/webworkers/compression.worker.js
+++ b/src/js/webworkers/compression.worker.js
@@ -1,8 +1,7 @@
-import { compressX64 } from "../core/lzstring";
 import { globalConfig } from "../core/config";
+import { compressX64 } from "../core/lzstring";
+import { computeCrc } from "../core/sensitive_utils.encrypt";
 import { compressObject } from "../savegame/savegame_compressor";
-import { CRC_PREFIX } from "../core/sensitive_utils.encrypt";
-import crc32 from "crc/crc32";
 
 function accessNestedPropertyReverse(obj, keys) {
     let result = obj;
@@ -31,7 +30,7 @@ function performJob(job, data) {
             const optimized = compressObject(data.obj);
             const stringified = JSON.stringify(optimized);
 
-            const checksum = CRC_PREFIX + crc32(stringified + salt).toString(16);
+            const checksum = computeCrc(stringified + salt);
             return data.compressionPrefix + compressX64(checksum + stringified);
         }
         default: