diff --git a/libs/remix-debug/src/storage/mappingPreimages.js b/libs/remix-debug/src/storage/mappingPreimages.js
index 513bdbf58f..94f95ae973 100644
--- a/libs/remix-debug/src/storage/mappingPreimages.js
+++ b/libs/remix-debug/src/storage/mappingPreimages.js
@@ -13,7 +13,7 @@ module.exports = {
   * @param {Function} callback  - calback
   * @return {Map} - solidity mapping location (e.g { "<mapping_slot>" : { "<mapping-key1>": preimageOf1 }, { "<mapping-key2>": preimageOf2 }, ... })
   */
-async function decodeMappingsKeys (web3, storage, corrections, callback) {
+async function decodeMappingsKeys (web3, storage, corrections) {
   const ret = {}
   if (!corrections.length) corrections.push({offset: 0, slot: 0})
   for (let hashedLoc in storage) {
@@ -38,7 +38,7 @@ async function decodeMappingsKeys (web3, storage, corrections, callback) {
       ret[mappingSlot][mappingKey] = preimage
     }
   }
-  callback(null, ret)
+  return ret
 }
 
 /**
diff --git a/libs/remix-debug/src/storage/storageResolver.js b/libs/remix-debug/src/storage/storageResolver.js
index 4cedf4fa69..8e8afaeea6 100644
--- a/libs/remix-debug/src/storage/storageResolver.js
+++ b/libs/remix-debug/src/storage/storageResolver.js
@@ -47,14 +47,9 @@ class StorageResolver {
       if (error) {
         return callback(error)
       }
-      mappingPreimages.decodeMappingsKeys(this.web3, storage, corrections, (error, mappings) => {
-        if (error) {
-          callback(error)
-        } else {
-          this.preimagesMappingByAddress[address] = mappings
-          callback(null, mappings)
-        }
-      })
+      const mappings = mappingPreimages.decodeMappingsKeys(this.web3, storage, corrections)
+      this.preimagesMappingByAddress[address] = mappings
+      callback(null, mappings)
     })
   }
 
diff --git a/libs/remix-debug/src/storage/storageViewer.js b/libs/remix-debug/src/storage/storageViewer.js
index 3f7aaec6b9..d46b0cfc3b 100644
--- a/libs/remix-debug/src/storage/storageViewer.js
+++ b/libs/remix-debug/src/storage/storageViewer.js
@@ -118,14 +118,9 @@ class StorageViewer {
     if (this.mappingsLocationChanges) {
       return callback(null, this.mappingsLocationChanges)
     }
-    mappingPreimages.decodeMappingsKeys(this.web3, storageChanges, corrections, (error, mappings) => {
-      if (!error) {
-        this.mappingsLocationChanges = mappings
-        return callback(null, this.mappingsLocationChanges)
-      } else {
-        callback(error)
-      }
-    })
+    const mappings = mappingPreimages.decodeMappingsKeys(this.web3, storageChanges, corrections)
+    this.mappingsLocationChanges = mappings
+    return callback(null, this.mappingsLocationChanges)
   }
 }