diff --git a/src/abstract-parser.cc b/src/abstract-parser.cc
index cedfb970..fc27e94d 100644
--- a/src/abstract-parser.cc
+++ b/src/abstract-parser.cc
@@ -63,17 +63,3 @@ AbstractParserPtr createParser(InStream &input)
     // GCC
     return make_unique<GccParser>(input);
 }
-
-EFileFormat Parser::inputFormat() const
-{
-    if (dynamic_cast<JsonParser *>(parser_.get()))
-        return FF_JSON;
-
-    if (dynamic_cast<CovParser *>(parser_.get()))
-        return FF_COVERITY;
-
-    if (dynamic_cast<GccParser *>(parser_.get()))
-        return FF_GCC;
-
-    return FF_INVALID;
-}
diff --git a/src/abstract-parser.hh b/src/abstract-parser.hh
index d3972080..2cace5bc 100644
--- a/src/abstract-parser.hh
+++ b/src/abstract-parser.hh
@@ -50,6 +50,10 @@ class AbstractParser {
             return emptyProps_;
         }
 
+        virtual EFileFormat inputFormat() const {
+            return FF_INVALID;
+        }
+
     protected:
         AbstractParser() = default;
 
@@ -91,7 +95,9 @@ class Parser {
             return parser_->getScanProps();
         }
 
-        EFileFormat inputFormat() const;
+        EFileFormat inputFormat() const {
+            return parser_->inputFormat();
+        };
 
     private:
         InStream                         &input_;
diff --git a/src/color.cc b/src/color.cc
index 0951f57a..9a4ae7c1 100644
--- a/src/color.cc
+++ b/src/color.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014 Red Hat, Inc.
+ * Copyright (C) 2014-2022 Red Hat, Inc.
  *
  * This file is part of csdiff.
  *
@@ -39,7 +39,7 @@ ColorWriter::ColorWriter(const std::ostream &str, const EColorMode cm)
     }
 }
 
-const char* ColorWriter::setColor(const EColor color)
+const char* ColorWriter::setColor(const EColor color) const
 {
     if (!enabled_)
         return "";
@@ -55,7 +55,7 @@ const char* ColorWriter::setColor(const EColor color)
     return "";
 }
 
-const char* ColorWriter::setColorIf(bool cond, const EColor color)
+const char* ColorWriter::setColorIf(bool cond, const EColor color) const
 {
     return (cond) ? this->setColor(color) : "";
 }
diff --git a/src/color.hh b/src/color.hh
index dd648df3..c20f7f76 100644
--- a/src/color.hh
+++ b/src/color.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014 Red Hat, Inc.
+ * Copyright (C) 2014-2022 Red Hat, Inc.
  *
  * This file is part of csdiff.
  *
@@ -39,8 +39,8 @@ enum EColor {
 class ColorWriter {
     public:
         ColorWriter(const std::ostream &str, EColorMode);
-        const char* setColor(EColor);
-        const char* setColorIf(bool, EColor);
+        const char* setColor(EColor) const;
+        const char* setColorIf(bool, EColor) const;
 
     private:
         bool enabled_;
diff --git a/src/csdiff.cc b/src/csdiff.cc
index 562883dd..a2de454a 100644
--- a/src/csdiff.cc
+++ b/src/csdiff.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011 Red Hat, Inc.
+ * Copyright (C) 2011-2022 Red Hat, Inc.
  *
  * This file is part of csdiff.
  *
@@ -37,7 +37,7 @@ int main(int argc, char *argv[])
     po::options_description desc(string("Usage: ") + name
             + " [options] old.err new.err, where options are");
 
-    typedef std::vector<string> TStringList;
+    using TStringList = std::vector<string>;
     string mode;
 
     try {
@@ -124,7 +124,7 @@ int main(int argc, char *argv[])
         const RE reSubst("([^,]+),(.*)");
         for (const string &subst : substList) {
             if (!boost::regex_match(subst, sm, reSubst)) {
-                std::cerr << "bad substutution format: " << subst
+                std::cerr << "bad substitution format: " << subst
                     << std::endl << "use: -s OLD,NEW" << std::endl;
                 return 1;
             }
diff --git a/src/csfilter.cc b/src/csfilter.cc
index 3a149701..b5ed822f 100644
--- a/src/csfilter.cc
+++ b/src/csfilter.cc
@@ -58,7 +58,7 @@ struct MsgReplace {
     }
 };
 
-typedef std::vector<MsgReplace>               TMsgReplaceList;
+using TMsgReplaceList = std::vector<MsgReplace>;
 
 struct MsgFilter::Private {
     bool ignorePath = false;
diff --git a/src/csfilter.hh b/src/csfilter.hh
index 00389700..7cad8d61 100644
--- a/src/csfilter.hh
+++ b/src/csfilter.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011 Red Hat, Inc.
+ * Copyright (C) 2011-2022 Red Hat, Inc.
  *
  * This file is part of csdiff.
  *
@@ -26,8 +26,8 @@
 #include <string>
 #include <vector>
 
-typedef std::vector<std::string> TStringList;
-typedef std::map<std::string, std::string> TSubstMap;
+using TStringList = std::vector<std::string>;
+using TSubstMap = std::map<std::string, std::string>;
 
 class MsgFilter {
     public:
diff --git a/src/csparser.hh b/src/csparser.hh
index 4eceed05..2146a232 100644
--- a/src/csparser.hh
+++ b/src/csparser.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011-2012 Red Hat, Inc.
+ * Copyright (C) 2011-2022 Red Hat, Inc.
  *
  * This file is part of csdiff.
  *
@@ -30,6 +30,10 @@ class CovParser: public AbstractParser {
         bool getNext(Defect *) override;
         bool hasError() const override;
 
+        EFileFormat inputFormat() const override {
+            return FF_COVERITY;
+        }
+
     private:
         CovParser(const Parser &);
         CovParser& operator=(const Parser &);
diff --git a/src/gcc-parser.hh b/src/gcc-parser.hh
index 559d063b..c6657632 100644
--- a/src/gcc-parser.hh
+++ b/src/gcc-parser.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2013 Red Hat, Inc.
+ * Copyright (C) 2013-2022 Red Hat, Inc.
  *
  * This file is part of csdiff.
  *
@@ -30,6 +30,10 @@ class GccParser: public AbstractParser {
         bool getNext(Defect *) override;
         bool hasError() const override;
 
+        EFileFormat inputFormat() const override {
+            return FF_GCC;
+        }
+
     private:
         GccParser(const Parser &);
         GccParser& operator=(const Parser &);
diff --git a/src/instream.cc b/src/instream.cc
index f73b8c27..576a661f 100644
--- a/src/instream.cc
+++ b/src/instream.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011 - 2021 Red Hat, Inc.
+ * Copyright (C) 2011 - 2022 Red Hat, Inc.
  *
  * This file is part of csdiff.
  *
@@ -19,16 +19,15 @@
 
 #include "instream.hh"
 
-InStream::InStream(const std::string &fileName, const bool silent):
-    fileName_(fileName),
+InStream::InStream(std::string fileName, const bool silent):
+    fileName_(std::move(fileName)),
     silent_(silent),
-    anyError_(false),
-    str_((!fileName_.compare("-"))
+    str_((fileName_ == "-")
                 ? std::cin
                 : fileStr_)
 {
     if (&str_ == &fileStr_)
-        fileStr_.open(fileName_, std::ios::in);
+        fileStr_.open(fileName_);
 
     if (!fileStr_)
         throw InFileException(fileName_);
@@ -36,18 +35,11 @@ InStream::InStream(const std::string &fileName, const bool silent):
 
 InStream::InStream(std::istringstream &str, const bool silent):
     silent_(silent),
-    anyError_(false),
     str_(str)
 {
 }
 
-InStream::~InStream()
-{
-    if (&str_ == &fileStr_)
-        fileStr_.close();
-}
-
-void InStream::handleError(const std::string msg, const long line)
+void InStream::handleError(const std::string &msg, const unsigned long line)
 {
     anyError_ = true;
     if (silent_ || msg.empty())
diff --git a/src/instream.hh b/src/instream.hh
index 48100e27..8abf8229 100644
--- a/src/instream.hh
+++ b/src/instream.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011 - 2021 Red Hat, Inc.
+ * Copyright (C) 2011 - 2022 Red Hat, Inc.
  *
  * This file is part of csdiff.
  *
@@ -38,29 +38,29 @@ struct InFileException {
 
 class InStream {
     public:
-        InStream(const std::string &fileName, bool silent = false);
+        InStream(std::string fileName, bool silent = false);
         InStream(std::istringstream &str, bool silent = false);
-        ~InStream();
+        ~InStream() = default;
 
         const std::string& fileName()   const { return fileName_;   }
         std::istream& str()             const { return str_;        }
         bool silent()                   const { return silent_;     }
         bool anyError()                 const { return anyError_;   }
 
-        void handleError(std::string msg = std::string(), long line = 0L);
+        void handleError(const std::string &msg = "", unsigned long line = 0UL);
 
     private:
         const std::string   fileName_;
         const bool          silent_;
-        bool                anyError_;
-        std::fstream        fileStr_;
+        bool                anyError_ = false;
+        std::ifstream       fileStr_;
         std::istream       &str_;
 };
 
 class InStreamLookAhead {
     public:
         InStreamLookAhead(
-                InStream       &inStr,
+                InStream       &input,
                 unsigned        size,
                 bool            skipWhiteSpaces = false);
 
diff --git a/src/json-parser.hh b/src/json-parser.hh
index 44439f09..0f4ad3ac 100644
--- a/src/json-parser.hh
+++ b/src/json-parser.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012 Red Hat, Inc.
+ * Copyright (C) 2012-2022 Red Hat, Inc.
  *
  * This file is part of csdiff.
  *
@@ -31,6 +31,10 @@ class JsonParser: public AbstractParser {
         bool hasError() const override;
         const TScanProps& getScanProps() const override;
 
+        EFileFormat inputFormat() const override {
+            return FF_JSON;
+        }
+
     private:
         JsonParser(const Parser &);
         JsonParser& operator=(const Parser &);