diff --git a/mkvwriteeofreader.cpp b/mkvwriteeofreader.cpp
index 62ebb21..ed42c63 100644
--- a/mkvwriteeofreader.cpp
+++ b/mkvwriteeofreader.cpp
@@ -18,7 +18,7 @@
 namespace mkvmuxer {
 
 MkvWriteEOFReader::MkvWriteEOFReader() : file_(NULL),
-                                             writes_allowed_(true) {
+                                         writes_allowed_(true) {
 }
 
 MkvWriteEOFReader::~MkvWriteEOFReader() {
diff --git a/sample_muxer_metadata.cc b/sample_muxer_metadata.cc
index c3a2e3f..212f9f0 100644
--- a/sample_muxer_metadata.cc
+++ b/sample_muxer_metadata.cc
@@ -2,8 +2,6 @@
 #include <string>
 #include "vttreader.h"
 
-using std::string;
-
 SampleMuxerMetadata::SampleMuxerMetadata() : segment_(NULL) {
 }
 
@@ -295,7 +293,7 @@ bool SampleMuxerMetadata::Parse(
   }
 }
 
-void SampleMuxerMetadata::MakeFrame(const cue_t& c, string* pf) {
+void SampleMuxerMetadata::MakeFrame(const cue_t& c, std::string* pf) {
   pf->clear();
   WriteCueIdentifier(c.identifier, pf);
   WriteCueSettings(c.settings, pf);
@@ -303,15 +301,15 @@ void SampleMuxerMetadata::MakeFrame(const cue_t& c, string* pf) {
 }
 
 void SampleMuxerMetadata::WriteCueIdentifier(
-    const string& identifier,
-    string* pf) {
+    const std::string& identifier,
+    std::string* pf) {
   pf->append(identifier);
   pf->push_back('\x0A');  // LF
 }
 
 void SampleMuxerMetadata::WriteCueSettings(
     const cue_t::settings_t& settings,
-    string* pf) {
+    std::string* pf) {
   if (settings.empty()) {
     pf->push_back('\x0A');  // LF
     return;
@@ -340,14 +338,14 @@ void SampleMuxerMetadata::WriteCueSettings(
 
 void SampleMuxerMetadata::WriteCuePayload(
     const cue_t::payload_t& payload,
-    string* pf) {
+    std::string* pf) {
   typedef cue_t::payload_t::const_iterator iter_t;
 
   iter_t i = payload.begin();
   const iter_t j = payload.end();
 
   while (i != j) {
-    const string& line = *i++;
+    const std::string& line = *i++;
     pf->append(line);
     pf->push_back('\x0A');  // LF
   }
@@ -370,7 +368,7 @@ bool SampleMuxerMetadata::SortableCue::Write(
   // Metadata blocks always specify the block duration.
   const mkvmuxer::int64 duration_ns = stop_ns - start_ns;
 
-  string frame;
+  std::string frame;
   MakeFrame(cue, &frame);
 
   typedef const mkvmuxer::uint8* data_t;
diff --git a/webvttparser.cc b/webvttparser.cc
index 18ca9e5..c26cd26 100644
--- a/webvttparser.cc
+++ b/webvttparser.cc
@@ -9,8 +9,6 @@
 #include "./webvttparser.h"  // NOLINT
 #include <climits>
 
-using std::string;
-
 namespace libwebvtt {
 
 enum {
@@ -27,11 +25,11 @@ Reader::~Reader() {
 LineReader::~LineReader() {
 }
 
-int LineReader::GetLine(string* line_ptr) {
+int LineReader::GetLine(std::string* line_ptr) {
   if (line_ptr == NULL)
     return -1;
 
-  string& ln = *line_ptr;
+  std::string& ln = *line_ptr;
   ln.clear();
 
   // Consume characters from the stream, until we
@@ -138,7 +136,7 @@ int Parser::Init() {
       return -1;
   }
 
-  string line;
+  std::string line;
 
   e = GetLine(&line);
 
@@ -181,7 +179,7 @@ int Parser::Parse(Cue* cue) {
 
   // Parse first non-blank line
 
-  string line;
+  std::string line;
   int e;
 
   for (;;) {
@@ -200,9 +198,9 @@ int Parser::Parse(Cue* cue) {
   // may not appear in the cue identifier line.
 
   const char kArrow[] = "-->";
-  string::size_type arrow_pos = line.find(kArrow);
+  std::string::size_type arrow_pos = line.find(kArrow);
 
-  if (arrow_pos != string::npos) {
+  if (arrow_pos != std::string::npos) {
     // We found a timings line, which implies that we don't have a cue
     // identifier.
 
@@ -224,7 +222,7 @@ int Parser::Parse(Cue* cue) {
 
     arrow_pos = line.find(kArrow);
 
-    if (arrow_pos == string::npos)  // not a timings line
+    if (arrow_pos == std::string::npos)  // not a timings line
       return -1;
   }
 
@@ -306,23 +304,23 @@ int Parser::ParseBOM() {
 }
 
 int Parser::ParseTimingsLine(
-    string* line_ptr,
-    string::size_type arrow_pos,
+    std::string* line_ptr,
+    std::string::size_type arrow_pos,
     Time* start_time,
     Time* stop_time,
     Cue::settings_t* settings) {
   if (line_ptr == NULL)
     return -1;
 
-  string& line = *line_ptr;
+  std::string& line = *line_ptr;
 
-  if (arrow_pos == string::npos || arrow_pos >= line.length())
+  if (arrow_pos == std::string::npos || arrow_pos >= line.length())
     return -1;
 
   // Place a NUL character at the start of the arrow token, in
   // order to demarcate the start time from remainder of line.
   line[arrow_pos] = kNUL;
-  string::size_type idx = 0;
+  std::string::size_type idx = 0;
 
   int e = ParseTime(line, &idx, start_time);
   if (e)  // error
@@ -356,15 +354,15 @@ int Parser::ParseTimingsLine(
 }
 
 int Parser::ParseTime(
-    const string& line,
-    string::size_type* idx_ptr,
+    const std::string& line,
+    std::string::size_type* idx_ptr,
     Time* time) {
   if (idx_ptr == NULL)
     return -1;
 
-  string::size_type& idx = *idx_ptr;
+  std::string::size_type& idx = *idx_ptr;
 
-  if (idx == string::npos || idx >= line.length())
+  if (idx == std::string::npos || idx >= line.length())
     return -1;
 
   if (time == NULL)
@@ -514,12 +512,12 @@ int Parser::ParseTime(
 }
 
 int Parser::ParseSettings(
-    const string& line,
-    string::size_type idx,
+    const std::string& line,
+    std::string::size_type idx,
     Cue::settings_t* settings) {
   settings->clear();
 
-  if (idx == string::npos || idx >= line.length())
+  if (idx == std::string::npos || idx >= line.length())
     return -1;
 
   for (;;) {
@@ -588,14 +586,14 @@ int Parser::ParseSettings(
 }
 
 int Parser::ParseNumber(
-    const string& line,
-    string::size_type* idx_ptr) {
+    const std::string& line,
+    std::string::size_type* idx_ptr) {
   if (idx_ptr == NULL)
     return -1;
 
-  string::size_type& idx = *idx_ptr;
+  std::string::size_type& idx = *idx_ptr;
 
-  if (idx == string::npos || idx >= line.length())
+  if (idx == std::string::npos || idx >= line.length())
     return -1;
 
   if (!isdigit(line[idx]))