diff --git a/src/V3EmitCBase.cpp b/src/V3EmitCBase.cpp
index 3c7ebc3d4..424fa82bd 100644
--- a/src/V3EmitCBase.cpp
+++ b/src/V3EmitCBase.cpp
@@ -67,6 +67,7 @@ AstCFile* EmitCBaseVisitorConst::createCFile(const string& filename, bool slow,
     AstCFile* const cfilep = new AstCFile{v3Global.rootp()->fileline(), filename};
     cfilep->slow(slow);
     cfilep->source(source);
+    if (source) V3Stats::addStatSum(V3Stats::STAT_CPP_FILES, 1);
     return cfilep;
 }
 
diff --git a/src/V3File.h b/src/V3File.h
index 9d1066a82..2106f908e 100644
--- a/src/V3File.h
+++ b/src/V3File.h
@@ -21,6 +21,7 @@
 #include "verilatedos.h"
 
 #include "V3Error.h"
+#include "V3Stats.h"
 
 #include <array>
 #include <fstream>
@@ -207,6 +208,7 @@ class V3OutFile VL_NOT_FINAL : public V3OutFormatter {
     // MEMBERS
     FILE* m_fp = nullptr;
     std::size_t m_usedBytes = 0;  // Number of bytes stored in m_bufferp
+    std::size_t m_writtenBytes = 0;  // Number of bytes written to output
     std::unique_ptr<std::array<char, WRITE_BUFFER_SIZE_BYTES>> m_bufferp;  // Write buffer
 
 public:
@@ -215,16 +217,23 @@ public:
     V3OutFile& operator=(const V3OutFile&) = delete;
     V3OutFile(V3OutFile&&) = delete;
     V3OutFile& operator=(V3OutFile&&) = delete;
-
     ~V3OutFile() override;
+
     void putsForceIncs();
 
+    void statRecordWritten() {
+        writeBlock();
+        V3Stats::addStatSum(V3Stats::STAT_CPP_CHARS, m_writtenBytes);
+    }
+
 private:
     void writeBlock() {
-        if (VL_LIKELY(m_usedBytes > 0)) fwrite(m_bufferp->data(), m_usedBytes, 1, m_fp);
-        m_usedBytes = 0;
+        if (VL_LIKELY(m_usedBytes > 0)) {
+            fwrite(m_bufferp->data(), m_usedBytes, 1, m_fp);
+            m_writtenBytes += m_usedBytes;
+            m_usedBytes = 0;
+        }
     }
-
     // CALLBACKS
     void putcOutput(char chr) override {
         m_bufferp->at(m_usedBytes++) = chr;
@@ -257,7 +266,7 @@ public:
         : V3OutFile{filename, lang} {
         resetPrivate();
     }
-    ~V3OutCFile() override = default;
+    ~V3OutCFile() override { statRecordWritten(); }
     virtual void putsHeader() { puts("// Verilated -*- C++ -*-\n"); }
     virtual void putsIntTopInclude() { putsForceIncs(); }
     virtual void putsGuard();
diff --git a/src/V3Stats.cpp b/src/V3Stats.cpp
index 0312c6458..0212d2816 100644
--- a/src/V3Stats.cpp
+++ b/src/V3Stats.cpp
@@ -23,6 +23,11 @@
 
 VL_DEFINE_DEBUG_FUNCTIONS;
 
+//######################################################################
+// Statics
+
+V3Mutex V3Stats::s_mutex;
+
 //######################################################################
 // Stats class functions
 
@@ -165,6 +170,11 @@ public:
 //######################################################################
 // Top Stats class
 
+void V3Stats::addStatSum(const string& name, double count) VL_MT_SAFE_EXCLUDES(s_mutex) {
+    V3LockGuard lock{s_mutex};
+    addStat(V3Statistic{"*", name, count, 0, true});
+}
+
 void V3Stats::statsStageAll(AstNetlist* nodep, const std::string& stage, bool fastOnly) {
     StatsVisitor{nodep, stage, fastOnly};
 }
diff --git a/src/V3Stats.h b/src/V3Stats.h
index 7c3a8ea1c..33f100723 100644
--- a/src/V3Stats.h
+++ b/src/V3Stats.h
@@ -103,8 +103,12 @@ public:
 //============================================================================
 
 class V3Stats final {
+    static V3Mutex s_mutex;  // Protects accesses
+
 public:
     // Symbolic names for some statistics that are later read by summaryReport()
+    static constexpr const char* STAT_CPP_CHARS = "Output, C++ bytes written";
+    static constexpr const char* STAT_CPP_FILES = "Output, C++ files written";
     static constexpr const char* STAT_MODEL_SIZE = "Size prediction, Model total (bytes)";
     static constexpr const char* STAT_SOURCE_CHARS = "Input, Verilog bytes read";
     static constexpr const char* STAT_SOURCE_MODULES = "Input, Verilog modules read";
@@ -117,9 +121,8 @@ public:
     static void addStat(const string& name, double value, unsigned precision = 0) {
         addStat(V3Statistic{"*", name, value, precision});
     }
-    static void addStatSum(const string& name, double count) {
-        addStat(V3Statistic{"*", name, count, 0, true});
-    }
+    // Add summary statistic - Threadsafe _unlike most other functions here_
+    static void addStatSum(const string& name, double count) VL_MT_SAFE_EXCLUDES(s_mutex);
     static void addStatPerf(const string& name, double value) {
         addStat(V3Statistic{"*", name, value, 6, true, true});
     }