diff --git a/tools/ld-disc-stacker/stackingpool.cpp b/tools/ld-disc-stacker/stackingpool.cpp
index 4440530a5..ad4256d31 100644
--- a/tools/ld-disc-stacker/stackingpool.cpp
+++ b/tools/ld-disc-stacker/stackingpool.cpp
@@ -23,6 +23,7 @@
 ************************************************************************/
 
 #include "stackingpool.h"
+#include "vbidecoder.h"
 
 StackingPool::StackingPool(QString _outputFilename, QString _outputJsonFilename,
                              qint32 _maxThreads, QVector<LdDecodeMetaData *> &_ldDecodeMetaData, QVector<SourceVideo *> &_sourceVideos,
diff --git a/tools/ld-dropout-correct/correctorpool.cpp b/tools/ld-dropout-correct/correctorpool.cpp
index ee98b5e15..81317eef5 100644
--- a/tools/ld-dropout-correct/correctorpool.cpp
+++ b/tools/ld-dropout-correct/correctorpool.cpp
@@ -24,6 +24,7 @@
 ************************************************************************/
 
 #include "correctorpool.h"
+#include "vbidecoder.h"
 
 CorrectorPool::CorrectorPool(QString _outputFilename, QString _outputJsonFilename,
                              qint32 _maxThreads, QVector<LdDecodeMetaData *> &_ldDecodeMetaData, QVector<SourceVideo *> &_sourceVideos,
diff --git a/tools/library/tbc/jsonio.cpp b/tools/library/tbc/jsonio.cpp
index 451c69473..45f6c30a9 100644
--- a/tools/library/tbc/jsonio.cpp
+++ b/tools/library/tbc/jsonio.cpp
@@ -24,8 +24,12 @@
 
 #include "jsonio.h"
 
-#include <cmath>
 #include <limits>
+#if ((defined(_MSVC_LANG) && _MSVC_LANG >= 201703L) || __cplusplus >= 201703L)
+#include <charconv>
+#else
+#include <sstream>
+#endif
 
 // Recognise JSON space characters
 static bool isAsciiSpace(char c)
@@ -46,10 +50,12 @@ JsonReader::JsonReader(std::istream &_input)
 
 void JsonReader::read(int &value)
 {
-    // Round to the nearest integer
-    double d;
-    readNumber(d);
-    value = static_cast<int>(std::lround(d));
+    readSignedInteger(value);
+}
+
+void JsonReader::read(qint64 &value)
+{
+    readSignedInteger(value);
 }
 
 void JsonReader::read(double &value)
@@ -331,8 +337,13 @@ void JsonReader::readNumber(double &value)
         }
     }
 
-    // XXX In C++17 we could use std::from_chars instead, which is slightly more efficient
-    value = std::stod(buf);
+#if ((defined(_MSVC_LANG) && _MSVC_LANG >= 201703L) || __cplusplus >= 201703L)
+    // Use the faster C++17 method if available.
+    std::from_chars(buf.data(), buf.data() + buf.size(), value);
+#else
+    std::istringstream(buf) >> value;
+#endif
+
 
     // We've read one character beyond the end of the number (there's no way to
     // tell where the end is otherwise), so we must unget the last char
@@ -351,6 +362,11 @@ void JsonWriter::write(int value)
     output << value;
 }
 
+void JsonWriter::write(qint64 value)
+{
+    output << value;
+}
+
 void JsonWriter::write(double value)
 {
     output << value;
diff --git a/tools/library/tbc/jsonio.h b/tools/library/tbc/jsonio.h
index 24b1d529d..87e30c991 100644
--- a/tools/library/tbc/jsonio.h
+++ b/tools/library/tbc/jsonio.h
@@ -32,6 +32,7 @@
 #include <stdexcept>
 #include <string>
 #include <stack>
+#include <cmath>
 
 class JsonReader
 {
@@ -51,6 +52,7 @@ class JsonReader
     }
 
     // Numbers
+    void read(qint64 &value);
     void read(int &value);
     void read(double &value);
 
@@ -81,6 +83,12 @@ class JsonReader
 
     void readString(std::string &value);
     void readNumber(double &value);
+    template <typename T> void readSignedInteger(T& value) {
+        // Round to the nearest integer
+        double d;
+        readNumber(d);
+        value = static_cast<T>(std::llround(d));
+    }
 
     // The input stream
     std::istream &input;
@@ -101,6 +109,7 @@ class JsonWriter
 
     // Numbers
     void write(int value);
+    void write(qint64 value);
     void write(double value);
 
     // Booleans
diff --git a/tools/library/tbc/lddecodemetadata.h b/tools/library/tbc/lddecodemetadata.h
index 7a3102b49..c6930fe48 100644
--- a/tools/library/tbc/lddecodemetadata.h
+++ b/tools/library/tbc/lddecodemetadata.h
@@ -33,7 +33,6 @@
 #include <QDebug>
 #include <array>
 
-#include "vbidecoder.h"
 #include "dropouts.h"
 
 class JsonReader;
@@ -202,8 +201,8 @@ class LdDecodeMetaData
         DropOuts dropOuts;
         bool pad = false;
 
-        qint32 diskLoc = -1;
-        qint32 fileLoc = -1;
+        double diskLoc = -1;
+        qint64 fileLoc = -1;
         qint32 decodeFaults = -1;
         qint32 efmTValues = -1;