diff --git a/tools/binpac/lib/binpac_buffer.h b/tools/binpac/lib/binpac_buffer.h
index f7cf012950..bd34c9769d 100644
--- a/tools/binpac/lib/binpac_buffer.h
+++ b/tools/binpac/lib/binpac_buffer.h
@@ -17,7 +17,7 @@ public:
         int contract_threshold;
     };
 
-    enum LineBreakStyle {
+    enum LineBreakStyle : uint8_t {
         CR_OR_LF,     // CR or LF or CRLF
         STRICT_CRLF,  // CR followed by LF
         CR_LF_NUL,    // CR or LF or CR-LF or CR-NUL
@@ -142,13 +142,13 @@ protected:
     LineBreakStyle linebreak_style_default;
     unsigned char linebreaker_;
 
-    enum {
+    enum : uint8_t {
         UNKNOWN_MODE,
         LINE_MODE,
         FRAME_MODE,
     } mode_;
 
-    enum {
+    enum : uint8_t {
         CR_OR_LF_0,
         CR_OR_LF_1,
         STRICT_CRLF_0,
@@ -163,7 +163,7 @@ protected:
     static Policy policy;
 };
 
-typedef FlowBuffer* flow_buffer_t;
+using flow_buffer_t = FlowBuffer*;
 
 } // namespace binpac
 
diff --git a/tools/binpac/lib/binpac_bytestring.h b/tools/binpac/lib/binpac_bytestring.h
index 6a33f2eb8f..152ef7c42c 100644
--- a/tools/binpac/lib/binpac_bytestring.h
+++ b/tools/binpac/lib/binpac_bytestring.h
@@ -3,7 +3,7 @@
 #ifndef binpac_bytestring_h
 #define binpac_bytestring_h
 
-#include <string.h>
+#include <cstring>
 #include <string>
 
 #include "binpac.h"
@@ -16,7 +16,7 @@ class datastring;
 template<class T>
 class const_datastring {
 public:
-    const_datastring() : begin_(0), end_(0) {}
+    const_datastring() : begin_(nullptr), end_(nullptr) {}
 
     const_datastring(T const* data, int length) : begin_(data), end_(data + length) {}
 
@@ -49,7 +49,7 @@ private:
     T const* end_;
 };
 
-typedef const_datastring<uint8> const_bytestring;
+using const_bytestring = const_datastring<uint8>;
 
 template<class T>
 class datastring {
@@ -65,6 +65,9 @@ public:
     explicit datastring(const_datastring<T> const& x) { set_const(x.begin(), x.length()); }
 
     datastring const& operator=(datastring<T> const& x) {
+        if ( this == &x )
+            return *this;
+
         BINPAC_ASSERT(! data_);
         set(x.data(), x.length());
         return *this;
@@ -76,7 +79,7 @@ public:
     }
 
     void clear() {
-        data_ = 0;
+        data_ = nullptr;
         length_ = 0;
     }
 
@@ -119,13 +122,11 @@ private:
     int length_;
 };
 
-typedef datastring<uint8> bytestring;
+using bytestring = datastring<uint8>;
 
 inline const char* c_str(bytestring const& s) { return (const char*)s.begin(); }
 
-inline std::string std_str(const_bytestring const& s) {
-    return std::string((const char*)s.begin(), (const char*)s.end());
-}
+inline std::string std_str(const_bytestring const& s) { return {(const char*)s.begin(), (const char*)s.end()}; }
 
 inline bool operator==(bytestring const& s1, const char* s2) { return strcmp(c_str(s1), s2) == 0; }
 
diff --git a/tools/binpac/lib/binpac_exception.h b/tools/binpac/lib/binpac_exception.h
index 8578ae83fc..52bd6f7421 100644
--- a/tools/binpac/lib/binpac_exception.h
+++ b/tools/binpac/lib/binpac_exception.h
@@ -3,25 +3,26 @@
 #ifndef binpac_exception_h
 #define binpac_exception_h
 
-#include <inttypes.h>
-#include <stdint.h>
+#include <cinttypes>
+#include <cstdint>
+#include <string>
 
 namespace binpac {
 
 class Exception {
 public:
-    Exception(const char* m = 0) : msg_("binpac exception: ") {
+    Exception(const char* m = nullptr) : msg_("binpac exception: ") {
         if ( m )
             append(m);
         // abort();
     }
 
-    void append(string m) { msg_ += m; }
-    string msg() const { return msg_; }
+    void append(std::string m) { msg_ += m; }
+    std::string msg() const { return msg_; }
     const char* c_msg() const { return msg_.c_str(); }
 
 protected:
-    string msg_;
+    std::string msg_;
 };
 
 class ExceptionEnforceViolation : public Exception {
@@ -46,7 +47,7 @@ public:
 protected:
     const char* location_;
     int64_t index_;
-    string expected_;
+    std::string expected_;
 };
 
 class ExceptionInvalidCaseIndex : public Exception {
diff --git a/tools/binpac/lib/binpac_regex.h b/tools/binpac/lib/binpac_regex.h
index d8e2a05c23..6e1ea11101 100644
--- a/tools/binpac/lib/binpac_regex.h
+++ b/tools/binpac/lib/binpac_regex.h
@@ -1,6 +1,10 @@
+// See the file "COPYING" in the main distribution directory for copyright.
+
 #ifndef binpac_regex_h
 #define binpac_regex_h
 
+#include <vector>
+
 #include "zeek/RE.h"
 
 #include "binpac.h"
@@ -16,7 +20,7 @@ namespace binpac {
 // Note, this must be declared/defined here, and inline, because the RE
 // functionality can only be used when compiling from inside Zeek.
 // A copy is made of any FlowBuffer policy struct data passed.
-inline void init(FlowBuffer::Policy* fbp = 0);
+inline void init(FlowBuffer::Policy* fbp = nullptr);
 
 // Internal vector recording not yet compiled matchers.
 extern std::vector<zeek::RE_Matcher*>* uncompiled_re_matchers;
@@ -50,8 +54,8 @@ inline void RegExMatcher::init() {
     if ( ! uncompiled_re_matchers )
         return;
 
-    for ( size_t i = 0; i < uncompiled_re_matchers->size(); ++i ) {
-        if ( ! (*uncompiled_re_matchers)[i]->Compile() ) {
+    for ( const auto& matcher : *uncompiled_re_matchers ) {
+        if ( ! matcher->Compile() ) {
             fprintf(stderr, "binpac: cannot compile regular expression\n");
             exit(1);
         }
diff --git a/tools/binpac/src/pac_main.cc b/tools/binpac/src/pac_main.cc
index 83cf8ba15c..f3e5847f52 100644
--- a/tools/binpac/src/pac_main.cc
+++ b/tools/binpac/src/pac_main.cc
@@ -3,7 +3,6 @@
 #include <ctype.h>
 #include <unistd.h>
 
-#include "config.h"
 #include "pac_common.h"
 #include "pac_decl.h"
 #include "pac_exception.h"
@@ -177,9 +176,6 @@ int compile(const char* filename) {
 }
 
 void usage() {
-#ifdef BINPAC_VERSION
-    fprintf(stderr, "binpac version %s\n", BINPAC_VERSION);
-#endif
     fprintf(stderr, "usage: binpac [options] <pac files>\n");
     fprintf(stderr, "     <pac files>           | pac-language input files\n");
     fprintf(stderr, "     -d <dir>              | use given directory for compiler output\n");