diff --git a/src/standaloneUtils/rmDuplicates.js b/src/standaloneUtils/rmDuplicates.js
index 7631204..5616e8e 100644
--- a/src/standaloneUtils/rmDuplicates.js
+++ b/src/standaloneUtils/rmDuplicates.js
@@ -4,6 +4,7 @@ const { addQuestion, doSearch } = require('../../dist/utils/classes.js') // esli
 const { loadData } = require('../../dist/utils/actions.js') // eslint-disable-line
 
 // Params [ 'publicDirs/qminingPublic/questionDbs/elektro.json' ]
+// load: 4.44ms
 // ==============================================================================================
 // 1 / 1: Elektronika, 826 questions
 // Result length: 0, original length: 826
@@ -11,21 +12,22 @@ const { loadData } = require('../../dist/utils/actions.js') // eslint-disable-li
 // Removed 11 questions
 // ==============================================================================================
 // Result length: 815, original length: 826, removed 11 questions
+// rmduplicates: 9.349s
 // File written
 
-// load: 15.605ms
+// load: 15.679ms
 // Removing duplicate questions from publicDirs/qminingPublic/questionDbs/elektro.json
 // ==============================================================================================
 // 1 / 1: Elektronika, 826 questions
 // Result length: 0, original length: 826
 //  [=====================================================================] 826 / 826
-// Removed 160 questions
+// Removed 10 questions
 // ==============================================================================================
-// Result length: 666, original length: 826, removed 160 questions
-// rmduplicates: 569.828ms
+// Result length: 816, original length: 826, removed 10 questions
+// rmduplicates: 493.23ms
 // File written
 
-const minpercent = 95
+const minpercent = 96
 const resultDbFileName = 'res.json'
 const line =
   '===================================================================='
diff --git a/src/utils/classes.ts b/src/utils/classes.ts
index a637034..335a287 100755
--- a/src/utils/classes.ts
+++ b/src/utils/classes.ts
@@ -118,7 +118,7 @@ function compareString(
     }
 
     const currMatchIndex = s2a.indexOf(s1a[i])
-    if (lastMatchIndex < currMatchIndex) {
+    if (currMatchIndex !== -1 && lastMatchIndex < currMatchIndex) {
       match++
       lastMatchIndex = currMatchIndex
     }