diff --git a/src/conf.c b/src/conf.c
index 7811d14..2b29750 100644
--- a/src/conf.c
+++ b/src/conf.c
@@ -384,13 +384,14 @@ static int h_external(int argc, unsigned char ** argv){
 static int h_log(int argc, unsigned char ** argv){
 	struct logger *lg;
 	ROTATION rotation = (argc > 2)? getrotate(*argv[2]) : NONE;
+	int err = 0;
 
 	/* the same log as before is not opened again */
-	lg = logget((argc > 1)? argv[1] : (unsigned char *)"", rotation);
+	lg = logget((argc > 1)? argv[1] : (unsigned char *)"", rotation, &err);
 	if(!lg){
 		fprintf(stderr, "Unable to open log %.*s: %s, line %d\n",
 			(int)logselen((argc > 1)? argv[1] : (unsigned char *)""),
-			(argc > 1)? (char *)argv[1] : "", strerror(errno), linenum);
+			(argc > 1)? (char *)argv[1] : "", strerror(err), linenum);
 		return 1;
 	}
 	if(conf->stacksize < lg->type->stacksize) conf->stacksize = lg->type->stacksize;
diff --git a/src/log.c b/src/log.c
index 4f649dc..47102b2 100644
--- a/src/log.c
+++ b/src/log.c
@@ -508,19 +508,29 @@ static int matchfile(const unsigned char *selector){
 	return 1;
 }
 
+/* errno of the C library: on Windows proxy.h makes errno the socket error */
+#ifdef _WIN32
+static int crterrno(void){
+	int e = 0;
+
+	_get_errno(&e);
+	return e;
+}
+#else
+#define crterrno() (errno)
+#endif
+
 static int fileinit(struct logger *lg){
 	unsigned char *name;
-	FILE *fp;
-	int err;
+	FILE *fp = NULL;
+	int err = 0;
 
-	if(!(name = malloc(LOGNAMESIZE))) return 21;
+	if(!(name = malloc(LOGNAMESIZE))) return ENOMEM;
 	dologname(name, lg->selector, NULL, lg->rotation, lg->rotated);
-	errno = ENAMETOOLONG;
-	fp = *name? fopen((char *)name, "a") : NULL;
-	err = errno;
+	if(!*name) err = ENAMETOOLONG;
+	else if(!(fp = fopen((char *)name, "a")) && !(err = crterrno())) err = EIO;
 	free(name);
-	errno = err;
-	if(!fp) return 1;
+	if(err) return err;
 	lg->data = fp;
 	return 0;
 }
@@ -671,7 +681,7 @@ void loginit(void){
 #ifndef _WIN32
 	_3proxy_mutex_init(&syslog_mutex);
 	/* kept for the life of the process, as every syslog logger is */
-	(void)logget((const unsigned char *)"@3proxy", NONE);
+	(void)logget((const unsigned char *)"@3proxy", NONE, NULL);
 #endif
 }
 
@@ -701,9 +711,9 @@ static void logsetparams(struct logger *lg, const unsigned char *params){
 }
 
 /* The logger named so, opened if none is: held until logput(). NULL, with
-   errno set, if it cannot be opened. A logger found with other parameters
-   takes the new ones. */
-struct logger *logget(const unsigned char *selector, ROTATION rotation){
+   the error in *errp (an errno value) unless it is NULL, if it cannot be
+   opened. A logger found with other parameters takes the new ones. */
+struct logger *logget(const unsigned char *selector, ROTATION rotation, int *errp){
 	struct logger *lg;
 	const struct logtype *type;
 	const unsigned char *params;
@@ -730,7 +740,7 @@ struct logger *logget(const unsigned char *selector, ROTATION rotation){
 			free(lg);
 		}
 		_3proxy_mutex_unlock(&log_mutex);
-		errno = ENOMEM;
+		if(errp) *errp = ENOMEM;
 		return NULL;
 	}
 	memcpy(lg->selector, selector, len);
@@ -745,13 +755,12 @@ struct logger *logget(const unsigned char *selector, ROTATION rotation){
 		lg->failtime = lg->rotated;
 	}
 	else if(err){
-		err = errno;
 		_3proxy_mutex_unlock(&log_mutex);
 		_3proxy_mutex_destroy(&lg->mutex);
 		if(lg->params) free(lg->params);
 		free(lg->selector);
 		free(lg);
-		errno = err;
+		if(errp) *errp = err;
 		return NULL;
 	}
 	lg->refs = 1;
diff --git a/src/mainconf.c b/src/mainconf.c
index 3dc1ea6..12d365d 100644
--- a/src/mainconf.c
+++ b/src/mainconf.c
@@ -318,12 +318,13 @@ static int srvprepare(struct srvstart *s, int argc, char **argv){
 		 case 'l':
 			{
 				struct logger *lg;
+				int err = 0;
 
 				/* the same log the log command, or another service,
 				   opened is shared with it */
-				if(!(lg = logget((unsigned char *)argv[i] + 2, NONE))){
+				if(!(lg = logget((unsigned char *)argv[i] + 2, NONE, &err))){
 					fprintf(stderr, "Unable to open log %.*s: %s\n",
-						(int)logselen((unsigned char *)argv[i] + 2), argv[i] + 2, strerror(errno));
+						(int)logselen((unsigned char *)argv[i] + 2), argv[i] + 2, strerror(err));
 					return 1;
 				}
 				logput(srv->logger);
diff --git a/src/proxy.h b/src/proxy.h
index 8acc4a8..08cda2b 100644
--- a/src/proxy.h
+++ b/src/proxy.h
@@ -346,7 +346,7 @@ void logdo(struct clientparam * param, const unsigned char *s);
 void logerror(const unsigned char *s);
 void loginit(void);
 void logtypeadd(const struct logtype *type);
-struct logger *logget(const unsigned char *selector, ROTATION rotation);
+struct logger *logget(const unsigned char *selector, ROTATION rotation, int *errp);
 void logref(struct logger *lg);
 void logput(struct logger *lg);
 void logcommit(struct extparam *c);
diff --git a/src/sql.c b/src/sql.c
index 4a92e0d..3289a37 100644
--- a/src/sql.c
+++ b/src/sql.c
@@ -101,7 +101,7 @@ static int odbcmatch(const unsigned char *selector){
 /* A data source down is not an error of the configuration: the log
    connects again later. */
 static int odbcinit(struct logger *lg){
-    if(!lg->data && !(lg->data = calloc(1, sizeof(struct logodbc)))) return 21;
+    if(!lg->data && !(lg->data = calloc(1, sizeof(struct logodbc)))) return ENOMEM;
     return odbcconnect(lg)? 0 : -1;
 }
 
diff --git a/src/structures.h b/src/structures.h
index c932db2..4f40749 100644
--- a/src/structures.h
+++ b/src/structures.h
@@ -635,8 +635,8 @@ struct hashtable {
 struct logtype {
 	const char *name;
 	int (*match)(const unsigned char *selector);
-	/* opens what it writes to, lg->data: 0, an error, or < 0 if it cannot
-	   be reached now but is to be tried again */
+	/* opens what it writes to, lg->data: 0, an error (an errno value), or
+	   < 0 if it cannot be reached now but is to be tried again */
 	int (*init)(struct logger *lg);
 	/* the line for a connection into buf, CLIENTTMPBUFSIZE: its length, -1
 	   for nothing to write; NULL if write() takes the connection itself */