diff --git a/base/base_tests/levenshtein_dfa_test.cpp b/base/base_tests/levenshtein_dfa_test.cpp
index 84374246de..99e0fbc716 100644
--- a/base/base_tests/levenshtein_dfa_test.cpp
+++ b/base/base_tests/levenshtein_dfa_test.cpp
@@ -22,16 +22,21 @@ enum class Status
 struct Result
 {
   Result() = default;
-  Result(Status status, size_t errorsMade = 0) : m_status(status), m_errorsMade(errorsMade) {}
+  Result(Status status, size_t errorsMade = 0, size_t prefixErrorsMade = 0)
+    : m_status(status), m_errorsMade(errorsMade), m_prefixErrorsMade(prefixErrorsMade)
+  {
+  }
 
   bool operator==(Result const & rhs) const
   {
     return m_status == rhs.m_status &&
-           (m_errorsMade == rhs.m_errorsMade || m_status == Status::Rejects);
+           (m_errorsMade == rhs.m_errorsMade || m_status == Status::Rejects) &&
+           (m_prefixErrorsMade == rhs.m_prefixErrorsMade || m_status == Status::Rejects);
   }
 
   Status m_status = Status::Accepts;
   size_t m_errorsMade = 0;
+  size_t m_prefixErrorsMade = 0;
 };
 
 string DebugPrint(Status status)
@@ -50,7 +55,8 @@ string DebugPrint(Result const & result)
   ostringstream os;
   os << "Result [ ";
   os << "status: " << DebugPrint(result.m_status) << ", ";
-  os << "errorsMade: " << result.m_errorsMade << " ]";
+  os << "errorsMade: " << result.m_errorsMade << ", ";
+  os << "prefixErrorsMade: " << result.m_prefixErrorsMade << " ]";
   return os.str();
 }
 
@@ -59,10 +65,10 @@ Result GetResult(LevenshteinDFA const & dfa, std::string const & s)
   auto it = dfa.Begin();
   DFAMove(it, s);
   if (it.Accepts())
-    return Result(Status::Accepts, it.ErrorsMade());
+    return Result(Status::Accepts, it.ErrorsMade(), it.PrefixErrorsMade());
   if (it.Rejects())
-    return Result(Status::Rejects, it.ErrorsMade());
-  return Result(Status::Intermediate, it.ErrorsMade());
+    return Result(Status::Rejects, it.ErrorsMade(), it.PrefixErrorsMade());
+  return Result(Status::Intermediate, it.ErrorsMade(), it.PrefixErrorsMade());
 }
 
 bool Accepts(LevenshteinDFA const & dfa, std::string const & s)
@@ -154,29 +160,39 @@ UNIT_TEST(LevenshteinDFA_ErrorsMade)
   {
     LevenshteinDFA dfa("москва", 1 /* prefixSize */, 2 /* maxErrors */);
 
-    TEST_EQUAL(GetResult(dfa, "москва"), Result(Status::Accepts, 0 /* errorsMade */), ());
-    TEST_EQUAL(GetResult(dfa, "москв"), Result(Status::Accepts, 1 /* errorsMade */), ());
-    TEST_EQUAL(GetResult(dfa, "моск"), Result(Status::Accepts, 2 /* errorsMade */), ());
+    TEST_EQUAL(GetResult(dfa, "москва"),
+               Result(Status::Accepts, 0 /* errorsMade */, 0 /* prefixErrorsMade */), ());
+    TEST_EQUAL(GetResult(dfa, "москв"),
+               Result(Status::Accepts, 1 /* errorsMade */, 0 /* prefixErrorsMade */), ());
+    TEST_EQUAL(GetResult(dfa, "моск"),
+               Result(Status::Accepts, 2 /* errorsMade */, 0 /* prefixErrorsMade */), ());
     TEST_EQUAL(GetResult(dfa, "мос").m_status, Status::Intermediate, ());
+    TEST_EQUAL(GetResult(dfa, "мос").m_prefixErrorsMade, 0, ());
 
-    TEST_EQUAL(GetResult(dfa, "моксав"), Result(Status::Accepts, 2 /* errorsMade */), ());
+    TEST_EQUAL(GetResult(dfa, "моксав"),
+               Result(Status::Accepts, 2 /* errorsMade */, 2 /* prefixErrorsMade */), ());
     TEST_EQUAL(GetResult(dfa, "максав").m_status, Status::Rejects, ());
 
     TEST_EQUAL(GetResult(dfa, "мсовк").m_status, Status::Intermediate, ());
-    TEST_EQUAL(GetResult(dfa, "мсовка"), Result(Status::Accepts, 2 /* errorsMade */), ());
+    TEST_EQUAL(GetResult(dfa, "мсовк").m_prefixErrorsMade, 2, ());
+    TEST_EQUAL(GetResult(dfa, "мсовка"),
+               Result(Status::Accepts, 2 /* errorsMade */, 2 /* prefixErrorsMade */), ());
     TEST_EQUAL(GetResult(dfa, "мсовкб").m_status, Status::Rejects, ());
   }
 
   {
     LevenshteinDFA dfa("aa", 0 /* prefixSize */, 2 /* maxErrors */);
-    TEST_EQUAL(GetResult(dfa, "abab"), Result(Status::Accepts, 2 /* errorsMade */), ());
+    TEST_EQUAL(GetResult(dfa, "abab"),
+               Result(Status::Accepts, 2 /* errorsMade */, 2 /* prefixErrorsMade */), ());
   }
 
   {
     LevenshteinDFA dfa("mississippi", 0 /* prefixSize */, 0 /* maxErrors */);
     TEST_EQUAL(GetResult(dfa, "misisipi").m_status, Status::Rejects, ());
     TEST_EQUAL(GetResult(dfa, "mississipp").m_status, Status::Intermediate, ());
-    TEST_EQUAL(GetResult(dfa, "mississippi"), Result(Status::Accepts, 0 /* errorsMade */), ());
+    TEST_EQUAL(GetResult(dfa, "mississipp").m_prefixErrorsMade, 0, ());
+    TEST_EQUAL(GetResult(dfa, "mississippi"),
+               Result(Status::Accepts, 0 /* errorsMade */, 0 /* prefixErrorsMade */), ());
   }
 
   {
@@ -185,9 +201,9 @@ UNIT_TEST(LevenshteinDFA_ErrorsMade)
     size_t const maxErrors = 1;
     string const str = "yekaterinburg";
     vector<pair<string, Result>> const queries = {
-        {"yekaterinburg", Result(Status::Accepts, 0 /* errorsMade */)},
-        {"ekaterinburg", Result(Status::Accepts, 1 /* errorsMade */)},
-        {"jekaterinburg", Result(Status::Accepts, 1 /* errorsMade */)},
+        {"yekaterinburg", Result(Status::Accepts, 0 /* errorsMade */, 0 /* prefixErrorsMade */)},
+        {"ekaterinburg", Result(Status::Accepts, 1 /* errorsMade */, 1 /* prefixErrorsMade */)},
+        {"jekaterinburg", Result(Status::Accepts, 1 /* errorsMade */, 1 /* prefixErrorsMade */)},
         {"iekaterinburg", Result(Status::Rejects)}};
 
     for (auto const & q : queries)
@@ -199,8 +215,10 @@ UNIT_TEST(LevenshteinDFA_ErrorsMade)
 
   {
     LevenshteinDFA dfa("кафе", 1 /* prefixSize */, 1 /* maxErrors */);
-    TEST_EQUAL(GetResult(dfa, "кафе"), Result(Status::Accepts, 0 /* errorsMade */), ());
-    TEST_EQUAL(GetResult(dfa, "кафер"), Result(Status::Accepts, 1 /* errorsMade */), ());
+    TEST_EQUAL(GetResult(dfa, "кафе"),
+               Result(Status::Accepts, 0 /* errorsMade */, 0 /* prefixErrorsMade */), ());
+    TEST_EQUAL(GetResult(dfa, "кафер"),
+               Result(Status::Accepts, 1 /* errorsMade */, 1 /* prefixErrorsMade */), ());
   }
 }
 
@@ -214,26 +232,33 @@ UNIT_TEST(LevenshteinDFA_PrefixDFAModifier)
 
     TEST(!it.Accepts(), ());
     TEST(!it.Rejects(), ());
+    TEST_EQUAL(it.PrefixErrorsMade(), 0, ());
+    // |maxErrors| for all non-accepting states.
+    TEST_EQUAL(it.ErrorsMade(), 2, ());
 
     DFAMove(it, "c");
     TEST(it.Accepts(), ());
     TEST(!it.Rejects(), ());
     TEST_EQUAL(it.ErrorsMade(), 2, ());
+    TEST_EQUAL(it.PrefixErrorsMade(), 0, ());
 
     DFAMove(it, "d");
     TEST(it.Accepts(), ());
     TEST(!it.Rejects(), ());
     TEST_EQUAL(it.ErrorsMade(), 1, ());
+    TEST_EQUAL(it.PrefixErrorsMade(), 0, ());
 
     DFAMove(it, "e");
     TEST(it.Accepts(), ());
     TEST(!it.Rejects(), ());
     TEST_EQUAL(it.ErrorsMade(), 0, ());
+    TEST_EQUAL(it.PrefixErrorsMade(), 0, ());
 
     DFAMove(it, "fghijklmn");
     TEST(it.Accepts(), ());
     TEST(!it.Rejects(), ());
     TEST_EQUAL(it.ErrorsMade(), 0, ());
+    TEST_EQUAL(it.PrefixErrorsMade(), 0, ());
   }
 }
 
diff --git a/base/dfa_helpers.hpp b/base/dfa_helpers.hpp
index 87ee1de2a6..12894f8f9d 100644
--- a/base/dfa_helpers.hpp
+++ b/base/dfa_helpers.hpp
@@ -62,6 +62,7 @@ public:
     bool Accepts() const { return m_accepts; }
     bool Rejects() const { return !Accepts() && m_it.Rejects(); }
     size_t ErrorsMade() const { return m_it.ErrorsMade(); }
+    size_t PrefixErrorsMade() const { return m_it.PrefixErrorsMade(); }
 
   private:
     friend class PrefixDFAModifier;
diff --git a/base/levenshtein_dfa.cpp b/base/levenshtein_dfa.cpp
index 070f104c9c..8c5055616f 100644
--- a/base/levenshtein_dfa.cpp
+++ b/base/levenshtein_dfa.cpp
@@ -237,6 +237,7 @@ LevenshteinDFA::LevenshteinDFA(UniString const & s, size_t prefixSize,
     m_transitions.emplace_back(m_alphabet.size());
     m_accepting.push_back(false);
     m_errorsMade.push_back(ErrorsMade(state));
+    m_prefixErrorsMade.push_back(PrefixErrorsMade(state));
   };
 
   pushState(MakeStart(), kStartingState);
@@ -351,6 +352,14 @@ size_t LevenshteinDFA::ErrorsMade(State const & s) const
   return errorsMade;
 }
 
+size_t LevenshteinDFA::PrefixErrorsMade(State const & s) const
+{
+  size_t errorsMade = m_maxErrors;
+  for (auto const & p : s.m_positions)
+    errorsMade = std::min(errorsMade, m_maxErrors - p.m_errorsLeft);
+  return errorsMade;
+}
+
 size_t LevenshteinDFA::Move(size_t s, UniChar c) const
 {
   ASSERT_GREATER(m_alphabet.size(), 0, ());
diff --git a/base/levenshtein_dfa.hpp b/base/levenshtein_dfa.hpp
index 5505c94b23..fa52fa89cf 100644
--- a/base/levenshtein_dfa.hpp
+++ b/base/levenshtein_dfa.hpp
@@ -82,6 +82,7 @@ public:
     bool Rejects() const { return m_dfa.IsRejecting(m_s); }
 
     size_t ErrorsMade() const { return m_dfa.ErrorsMade(m_s); }
+    size_t PrefixErrorsMade() const { return m_dfa.PrefixErrorsMade(m_s); }
 
   private:
     friend class LevenshteinDFA;
@@ -126,6 +127,10 @@ private:
   size_t ErrorsMade(State const & s) const;
   size_t ErrorsMade(size_t s) const { return m_errorsMade[s]; }
 
+  // Returns minimum number of errors already made. This number cannot decrease.
+  size_t PrefixErrorsMade(State const & s) const;
+  size_t PrefixErrorsMade(size_t s) const { return m_prefixErrorsMade[s]; }
+
   size_t Move(size_t s, UniChar c) const;
 
   size_t const m_size;
@@ -136,6 +141,7 @@ private:
   std::vector<std::vector<size_t>> m_transitions;
   std::vector<bool> m_accepting;
   std::vector<size_t> m_errorsMade;
+  std::vector<size_t> m_prefixErrorsMade;
 };
 
 std::string DebugPrint(LevenshteinDFA::Position const & p);
diff --git a/base/uni_string_dfa.hpp b/base/uni_string_dfa.hpp
index 57765aab90..6187e8562a 100644
--- a/base/uni_string_dfa.hpp
+++ b/base/uni_string_dfa.hpp
@@ -19,6 +19,7 @@ public:
     bool Accepts() const { return !Rejects() && m_pos == m_s.size(); }
     bool Rejects() const { return m_rejected; }
     size_t ErrorsMade() const { return 0; }
+    size_t PrefixErrorsMade() const { return 0; }
 
   private:
     friend class UniStringDFA;