diff --git a/src/bitparser.cpp b/src/bitparser.cpp
index 58a44a7..c985237 100644
--- a/src/bitparser.cpp
+++ b/src/bitparser.cpp
@@ -14,7 +14,7 @@ using namespace std;
 #define display(...) \
 	do { if (_verbose) fprintf(stdout, __VA_ARGS__);} while(0)
 
-BitParser::BitParser(string filename, bool verbose):
+BitParser::BitParser(const string &filename, bool verbose):
 	ConfigBitstreamParser(filename, ConfigBitstreamParser::BIN_MODE,
 	verbose), fieldA(), part_name(), date(), hour(),
 	design_name(), userID(), toolVersion()
diff --git a/src/bitparser.hpp b/src/bitparser.hpp
index d4f4e74..c92707d 100644
--- a/src/bitparser.hpp
+++ b/src/bitparser.hpp
@@ -8,9 +8,9 @@
 
 class BitParser: public ConfigBitstreamParser {
 	public:
-		BitParser(std::string filename, bool verbose = false);
+		BitParser(const std::string &filename, bool verbose = false);
 		~BitParser();
-		int parse();
+		int parse() override;
 
 	private:
 		int parseField();
diff --git a/src/configBitstreamParser.cpp b/src/configBitstreamParser.cpp
index 4cb8a44..0c2d031 100644
--- a/src/configBitstreamParser.cpp
+++ b/src/configBitstreamParser.cpp
@@ -6,7 +6,7 @@
 
 using namespace std;
 
-ConfigBitstreamParser::ConfigBitstreamParser(string filename, int mode,
+ConfigBitstreamParser::ConfigBitstreamParser(const string &filename, int mode,
 			bool verbose):
 			_filename(filename), _bit_length(0),
 			_file_size(0), _verbose(verbose), _fd(filename,
diff --git a/src/configBitstreamParser.hpp b/src/configBitstreamParser.hpp
index 8744669..b122504 100644
--- a/src/configBitstreamParser.hpp
+++ b/src/configBitstreamParser.hpp
@@ -8,7 +8,7 @@
 
 class ConfigBitstreamParser {
 	public:
-		ConfigBitstreamParser(std::string filename, int mode = ASCII_MODE,
+		ConfigBitstreamParser(const std::string &filename, int mode = ASCII_MODE,
 			bool verbose = false);
 		virtual ~ConfigBitstreamParser();
 		virtual int parse() = 0;
diff --git a/src/mcsParser.cpp b/src/mcsParser.cpp
index fe15eca..e913494 100644
--- a/src/mcsParser.cpp
+++ b/src/mcsParser.cpp
@@ -41,7 +41,7 @@ using namespace std;
 #define TYPE_BASE 7
 #define DATA_BASE 9
 
-McsParser::McsParser(string filename, bool reverseOrder, bool verbose):
+McsParser::McsParser(const string &filename, bool reverseOrder, bool verbose):
 		ConfigBitstreamParser(filename, ConfigBitstreamParser::ASCII_MODE,
 		verbose),
 		_base_addr(0), _reverseOrder(reverseOrder)
@@ -61,7 +61,6 @@ int McsParser::parse()
 
 int McsParser::parseLine(string buffer)
 {
-	char *ptr;
 	const char *buff = buffer.c_str();
 	uint16_t tmp, byteLen, type, checksum;
 	uint32_t addr, loc_addr;
@@ -84,7 +83,7 @@ int McsParser::parseLine(string buffer)
 
 	if (type == 0) {
 		loc_addr = _base_addr + addr;
-		ptr = (char *)(buff + DATA_BASE);
+		char *ptr = (char *)(buff + DATA_BASE);
 		for (int i = 0; i < byteLen; i++, ptr += 2) {
 			sscanf(ptr, "%2hx", &tmp);
 			_bit_data[loc_addr + i] = (_reverseOrder)? reverseByte(tmp):tmp;
diff --git a/src/mcsParser.hpp b/src/mcsParser.hpp
index 9808458..5998cf3 100644
--- a/src/mcsParser.hpp
+++ b/src/mcsParser.hpp
@@ -22,8 +22,8 @@
 
 class McsParser: public ConfigBitstreamParser {
 	public:
-		McsParser(std::string filename, bool reverseOrder, bool verbose);
-		int parse();
+		McsParser(const std::string &filename, bool reverseOrder, bool verbose);
+		int parse() override;
 
 	private:
 		int parseLine(std::string buffer);