diff --git a/windows/tools/hresultwrap.cpp b/windows/tools/hresultwrap.cpp
index 04daad5f..e8675937 100644
--- a/windows/tools/hresultwrap.cpp
+++ b/windows/tools/hresultwrap.cpp
@@ -1,8 +1,7 @@
 // 21 may 2018
 #include <vector>
 #include <stdio.h>
-#include <string.h>
-#include "scanner.hpp"
+#include "lib.hpp"
 
 bool generate(const char *line, size_t n, FILE *fout)
 {
@@ -34,20 +33,20 @@ bool process(const char *line, size_t n, FILE *fout)
 
 int main(int argc, char *argv[])
 {
-	int fin = -1;
+	ReadCloser *fin = NULL;
 	FILE *fout = NULL;
 	Scanner *s = NULL;
 	int ret = 1;
-	int err;
+	Error *err = NULL;
 
 	if (argc != 3) {
 		fprintf(stderr, "usage: %s infile outfile\n", argv[0]);
 		return 1;
 	}
 
-	err = OpenForScanner(argv[1], &fin);
-	if (err != 0) {
-		fprintf(stderr, "error opening %s: %s\n", argv[1], strerror(err));
+	err = OpenRead(argv[1], &fin);
+	if (err != NULL) {
+		fprintf(stderr, "error opening %s: %s\n", argv[1], err->String());
 		goto done;
 	}
 	fout = fopen(argv[2], "wb");
@@ -68,8 +67,8 @@ int main(int argc, char *argv[])
 			goto done;
 		}
 	}
-	if (s->Error() != 0) {
-		fprintf(stderr, "error reading from %s: %s\n", argv[1], strerror(s->Error()));
+	if (s->Err() != 0) {
+		fprintf(stderr, "error reading from %s: %s\n", argv[1], s->Err()->String());
 		goto done;
 	}
 
@@ -79,7 +78,9 @@ done:
 		delete s;
 	if (fout != NULL)
 		fclose(fout);
-	if (fin >= 0)
-		CloseForScanner(fin);
+	if (fin != NULL)
+		delete fin;
+	if (err != NULL)
+		delete err;
 	return ret;
 }
diff --git a/windows/tools/lib.cpp b/windows/tools/lib.cpp
index 01a63907..b548f3c5 100644
--- a/windows/tools/lib.cpp
+++ b/windows/tools/lib.cpp
@@ -22,12 +22,12 @@ public:
 	virtual const char *String(void) const;
 };
 
-virtual ~eofError::eofError(void)
+eofError::~eofError(void)
 {
 	// do nothing
 }
 
-virtual const char *eofError::String(void) const
+const char *eofError::String(void) const
 {
 	return "EOF";
 }
@@ -39,12 +39,12 @@ public:
 	virtual const char *String(void) const;
 };
 
-virtual ~shortWriteError::shortWriteError(void)
+shortWriteError::~shortWriteError(void)
 {
 	// do nothing
 }
 
-virtual const char *shortWriteError::String(void) const
+const char *shortWriteError::String(void) const
 {
 	return "short write";
 }
@@ -61,7 +61,8 @@ Error *NewErrShortWrite(void)
 
 bool IsEOF(Error *e)
 {
-	return typeid (e) == typeid (eofError *);
+	// typeid does not work directly with pointers, alas (see https://stackoverflow.com/questions/4202877/typeid-for-polymorphic-types)
+	return typeid (*e) == typeid (eofError);
 }
 
 #define nbuf 1024
@@ -73,7 +74,7 @@ Scanner::Scanner(ReadCloser *r)
 	this->p = this->buf;
 	this->n = 0;
 	this->line = new std::vector<char>;
-	this->error = NULL;
+	this->err = NULL;
 }
 
 Scanner::~Scanner(void)
@@ -86,7 +87,7 @@ Scanner::~Scanner(void)
 
 bool Scanner::Scan(void)
 {
-	readtype n;
+	size_t n;
 
 	if (this->err != NULL)
 		return false;
@@ -132,7 +133,7 @@ size_t Scanner::Len(void) const
 	return this->line->size();
 }
 
-int Scanner::Err(void) const
+Error *Scanner::Err(void) const
 {
 	if (!IsEOF(this->err))
 		return this->err;
diff --git a/windows/tools/lib.hpp b/windows/tools/lib.hpp
index 1d9228e9..b8b8f3bf 100644
--- a/windows/tools/lib.hpp
+++ b/windows/tools/lib.hpp
@@ -3,7 +3,7 @@
 
 class Error {
 public:
-	virtual ~Error(void);
+	virtual ~Error(void) = default;
 
 	virtual const char *String(void) const = 0;
 };
@@ -14,14 +14,14 @@ extern bool IsEOF(Error *e);
 
 class ReadCloser {
 public:
-	virtual ~ReadCloser(void);
+	virtual ~ReadCloser(void) = default;
 
 	virtual Error *Read(void *buf, size_t n, size_t *actual) = 0;
 };
 
 class WriteCloser {
 public:
-	virtual ~WriteCloser(void);
+	virtual ~WriteCloser(void) = default;
 
 	virtual Error *Write(void *buf, size_t n) = 0;
 };
diff --git a/windows/tools/lib_posix.cpp b/windows/tools/lib_posix.cpp
index 30943a34..a743af9b 100644
--- a/windows/tools/lib_posix.cpp
+++ b/windows/tools/lib_posix.cpp
@@ -19,12 +19,12 @@ posixError::posixError(int error)
 	this->error = error;
 }
 
-virtual posixError::~posixError(void)
+posixError::~posixError(void)
 {
 	// do nothing
 }
 
-virtual const char *posixError::String(void) const
+const char *posixError::String(void) const
 {
 	return strerror(this->error);
 }
@@ -43,12 +43,12 @@ posixReadCloser::posixReadCloser(int fd)
 	this->fd = fd;
 }
 
-virtual posixReadCloser::~posixReadCloser(void)
+posixReadCloser::~posixReadCloser(void)
 {
 	close(this->fd);
 }
 
-virtual Error *posixReadCloser::Read(void *buf, size_t n, size_t *actual)
+Error *posixReadCloser::Read(void *buf, size_t n, size_t *actual)
 {
 	ssize_t ret;
 
@@ -57,7 +57,7 @@ virtual Error *posixReadCloser::Read(void *buf, size_t n, size_t *actual)
 	if (ret < 0)
 		return new posixError(errno);
 	if (ret == 0)
-		return NewEOF(void);
+		return NewEOF();
 	*actual = ret;
 	return NULL;
 }
@@ -68,7 +68,7 @@ public:
 	posixWriteCloser(int fd);
 	virtual ~posixWriteCloser(void);
 
-	virtual Error *Write(void *buf, size_t n, size_t *actual);
+	virtual Error *Write(void *buf, size_t n);
 };
 
 posixWriteCloser::posixWriteCloser(int fd)
@@ -76,20 +76,20 @@ posixWriteCloser::posixWriteCloser(int fd)
 	this->fd = fd;
 }
 
-virtual posixWriteCloser::~posixWriteCloser(void)
+posixWriteCloser::~posixWriteCloser(void)
 {
 	close(this->fd);
 }
 
-virtual Error *posixWriteCloser::Write(void *buf, size_t n)
+Error *posixWriteCloser::Write(void *buf, size_t n)
 {
 	ssize_t ret;
 
 	ret = write(this->fd, buf, n);
 	if (ret < 0)
 		return new posixError(errno);
-	if (ret != n)
-		return NewErrShortWrite(void);
+	if (((size_t) ret) != n)
+		return NewErrShortWrite();
 	return NULL;
 }