diff --git a/network.c b/network.c
index ab23d1d..4cff9f4 100644
--- a/network.c
+++ b/network.c
@@ -24,7 +24,7 @@ static int fwd_sock;
 static char *tx_buf, *rx_buf;
 static int tx_pos;
 
-int net_submit(const char *hostname, char *plugin, char *filename, int ds_id, char *data)
+int net_submit(const char *hostname, const char *plugin, const char *filename, int ds_id, const char *data)
 {
 	int size = snprintf(tx_buf + tx_pos, BUFSIZE - tx_pos, "%s:%s:%s:%d %s\n",
 				hostname, plugin, filename, ds_id, data);
@@ -39,7 +39,7 @@ int net_submit(const char *hostname, char *plugin, char *filename, int ds_id, ch
 	return 0;
 }
 
-int net_submit_flush()
+int net_submit_flush(void)
 {
 	if (tx_pos != 0)
 		sendto(fwd_sock, tx_buf, tx_pos, 0, (struct sockaddr *)&fwd_sa, sizeof(fwd_sa));
@@ -76,7 +76,7 @@ int net_receive(int socket)
 	return 0;
 }
 
-static int net_config_get_saddr(char *section, char *option, struct sockaddr_in *sa)
+static int net_config_get_saddr(const char *section, const char *option, struct sockaddr_in *sa)
 {
 	char *part[2];
 
@@ -94,7 +94,7 @@ static int net_config_get_saddr(char *section, char *option, struct sockaddr_in
 	return 0;
 }
 
-int net_init_cli()
+int net_init_cli(void)
 {
 	int ret = net_config_get_saddr("global", "forward", &fwd_sa);
 	if (ret < 0)
@@ -118,7 +118,7 @@ int net_init_cli()
 	return 0;
 }
 
-int net_init_srv()
+int net_init_srv(void)
 {
 	struct sockaddr_in sa_srv;
 
diff --git a/network.h b/network.h
index 8ca49fb..45d0a08 100644
--- a/network.h
+++ b/network.h
@@ -3,11 +3,11 @@
 
 #include "plugins.h"
 
-int net_init_srv();
-int net_init_cli();
+int net_init_srv(void);
+int net_init_cli(void);
 int net_receive(int sock);
 
-int net_submit(const char *hostname, char *plugin, char *filename, int ds_id, char *data);
+int net_submit(const char *hostname, const char *plugin, const char *filename, int ds_id, const char *data);
 int net_submit_flush();
 
 #endif /* _NETWORK_H_ */
diff --git a/p_apache.c b/p_apache.c
index 25c0074..078cdfc 100644
--- a/p_apache.c
+++ b/p_apache.c
@@ -39,7 +39,7 @@ struct server_entry {
 
 static LIST_HEAD(server_list);
 
-static char *ds_def = {
+static const char *ds_def = {
 	"DS:total_accesses:COUNTER:90:0:U "
 	"DS:total_kbytes:COUNTER:90:0:U "
 	"DS:busy_workers:GAUGE:90:0:U "
@@ -58,7 +58,7 @@ struct sammler_plugin plugin;
 static char *rx_buf;
 static int rx_pos;
 
-static char * get_ds(int ds_id)
+static const char * get_ds(int ds_id)
 {
 	return ds_def;
 }
diff --git a/p_ctstat.c b/p_ctstat.c
index 09a14e3..34767eb 100644
--- a/p_ctstat.c
+++ b/p_ctstat.c
@@ -28,7 +28,7 @@
 
 struct sammler_plugin plugin;
 
-static char *ds_def = {
+static const char *ds_def = {
 	"DS:entries:GAUGE:15:0:U "
 	"DS:searched:DERIVE:15:0:U "
 	"DS:found:DERIVE:15:0:U "
@@ -47,7 +47,7 @@ static char *ds_def = {
 	"DS:expect_delete:DERIVE:15:0:U "
 };
 
-static char * get_ds(int ds_id)
+static const char * get_ds(int ds_id)
 {
 	return ds_def;
 }
diff --git a/p_load.c b/p_load.c
index baac5ba..1b19ac7 100644
--- a/p_load.c
+++ b/p_load.c
@@ -25,13 +25,13 @@
 
 struct sammler_plugin plugin;
 
-static char *ds_def = {
+static const char *ds_def = {
 	"DS:1min:GAUGE:15:0:U "
 	"DS:5min:GAUGE:15:0:U "
 	"DS:15min:GAUGE:15:0:U "
 };
 
-static char * get_ds(int ds_id)
+static const char * get_ds(int ds_id)
 {
 	return ds_def;
 }
diff --git a/p_memory.c b/p_memory.c
index 767eee5..c0fd9e8 100644
--- a/p_memory.c
+++ b/p_memory.c
@@ -30,19 +30,19 @@
 
 struct sammler_plugin plugin;
 
-static char *mem_ds_def = {
+static const char *mem_ds_def = {
 	"DS:total:GAUGE:15:0:U "
 	"DS:free:GAUGE:15:0:U "
 	"DS:buffers:GAUGE:15:0:U "
 	"DS:cached:GAUGE:15:0:U "
 };
 
-static char *swap_ds_def = {
+static const char *swap_ds_def = {
 	"DS:total:GAUGE:15:0:U "
 	"DS:free:GAUGE:15:0:U "
 };
 
-static char * get_ds(int ds_id)
+static const char * get_ds(int ds_id)
 {
 	switch (ds_id) {
 	case DS_MEMORY:
diff --git a/p_mount.c b/p_mount.c
index a174cf5..b797e55 100644
--- a/p_mount.c
+++ b/p_mount.c
@@ -27,12 +27,12 @@
 
 struct sammler_plugin plugin;
 
-static char *ds_def = {
+static const char *ds_def = {
 	"DS:block_total:GAUGE:15:0:U "
 	"DS:block_free:GAUGE:15:0:U "
 };
 
-static char * get_ds(int ds_id)
+static const char * get_ds(int ds_id)
 {
 	return ds_def;
 }
diff --git a/p_mysql.c b/p_mysql.c
index df0f7c5..1919cc8 100644
--- a/p_mysql.c
+++ b/p_mysql.c
@@ -41,12 +41,12 @@ struct server_entry {
 
 static LIST_HEAD(server_list);
 
-static char *traffic_ds_def = {
+static const char *traffic_ds_def = {
 	"DS:bytes_received:COUNTER:90:0:U "
 	"DS:bytes_sent:COUNTER:90:0:U "
 };
 
-static char *commands_ds_def = {
+static const char *commands_ds_def = {
 	"DS:com_delete:COUNTER:90:0:U "
 	"DS:com_insert:COUNTER:90:0:U "
 	"DS:com_select:COUNTER:90:0:U "
@@ -55,7 +55,7 @@ static char *commands_ds_def = {
 	"DS:questions:COUNTER:90:0:U "
 };
 
-static char *qcache_ds_def = {
+static const char *qcache_ds_def = {
 	"DS:qc_free_blocks:GAUGE:90:0:U "
 	"DS:qc_free_memory:GAUGE:90:0:U "
 	"DS:qc_hits:COUNTER:90:0:U "
@@ -66,14 +66,14 @@ static char *qcache_ds_def = {
 	"DS:qc_total_blocks:GAUGE:90:0:U "
 };
 
-static char *threads_ds_def = {
+static const char *threads_ds_def = {
 	"DS:threads_cached:GAUGE:90:0:U "
 	"DS:threads_connected:GAUGE:90:0:U "
 	"DS:threads_created:COUNTER:90:0:U "
 	"DS:threads_running:GAUGE:90:0:U "
 };
 
-static char * get_ds(int ds_id)
+static const char * get_ds(int ds_id)
 {
 	switch (ds_id) {
 	case DS_TRAFFIC:
diff --git a/p_mysql_helper.c b/p_mysql_helper.c
index e61f9e8..2c1faee 100644
--- a/p_mysql_helper.c
+++ b/p_mysql_helper.c
@@ -7,7 +7,7 @@
 #include "logging.h"
 #include "p_mysql_helper.h"
 
-void * init_connection(char *host, char *user, char *pass)
+void * init_connection(const char *host, const char *user, const char *pass)
 {
 	MYSQL *con = NULL;
 
diff --git a/p_mysql_helper.h b/p_mysql_helper.h
index 55168cf..248b971 100644
--- a/p_mysql_helper.h
+++ b/p_mysql_helper.h
@@ -26,7 +26,7 @@ struct mysql_stats {
 	uint64_t threads_running;
 };
 
-void * init_connection(char *host, char *user, char *pass);
+void * init_connection(const char *host, const char *user, const char *pass);
 int ping_connection(void *mysql);
 int close_connection(void *mysql);
 
diff --git a/p_netdev.c b/p_netdev.c
index 9a5c92e..b4a221f 100644
--- a/p_netdev.c
+++ b/p_netdev.c
@@ -28,14 +28,14 @@
 
 struct sammler_plugin plugin;
 
-static char *ds_def = {
+static const char *ds_def = {
 	"DS:byte_in:COUNTER:15:0:U "
 	"DS:byte_out:COUNTER:15:0:U "
 	"DS:pkt_in:COUNTER:15:0:U "
 	"DS:pkt_out:COUNTER:15:0:U "
 };
 
-static char * get_ds(int ds_id)
+static const char * get_ds(int ds_id)
 {
 	return ds_def;
 }
diff --git a/p_random.c b/p_random.c
index 0b37831..2ee1d14 100644
--- a/p_random.c
+++ b/p_random.c
@@ -25,11 +25,11 @@
 
 struct sammler_plugin plugin;
 
-static char *ds_def = {
+static const char *ds_def = {
 	"DS:entropy:GAUGE:15:0:U "
 };
 
-static char * get_ds(int ds_id)
+static const char * get_ds(int ds_id)
 {
 	return ds_def;
 }
diff --git a/p_rtstat.c b/p_rtstat.c
index eb0ad1e..c3a4d7a 100644
--- a/p_rtstat.c
+++ b/p_rtstat.c
@@ -31,7 +31,7 @@
 
 struct sammler_plugin plugin;
 
-static char *ds_def_stat = {
+static const char *ds_def_stat = {
 	"DS:in_hit:DERIVE:15:0:U "
 	"DS:in_slow_tot:DERIVE:15:0:U "
 	"DS:in_slow_mc:DERIVE:15:0:U "
@@ -46,7 +46,7 @@ static char *ds_def_stat = {
 	"DS:out_hlist_search:DERIVE:15:0:U "
 };
 
-static char *ds_def_gc = {
+static const char *ds_def_gc = {
 	"DS:entries:GAUGE:15:0:U "
 	"DS:gc_total:DERIVE:15:0:U "
 	"DS:gc_ignored:DERIVE:15:0:U "
@@ -54,7 +54,7 @@ static char *ds_def_gc = {
 	"DS:gc_dst_overflow:DERIVE:15:0:U "
 };
 
-static char * get_ds(int ds_id)
+static const char * get_ds(int ds_id)
 {
 	switch (ds_id) {
 	case DS_STAT:
diff --git a/p_stat.c b/p_stat.c
index 7beae4a..71cad77 100644
--- a/p_stat.c
+++ b/p_stat.c
@@ -31,7 +31,7 @@
 
 struct sammler_plugin plugin;
 
-static char *cpu_ds_def = {
+static const char *cpu_ds_def = {
 	"DS:user:COUNTER:15:0:U "
 	"DS:nice:COUNTER:15:0:U "
 	"DS:system:COUNTER:15:0:U "
@@ -42,13 +42,13 @@ static char *cpu_ds_def = {
 	"DS:steal:COUNTER:15:0:U "
 };
 
-static char *proc_ds_def = {
+static const char *proc_ds_def = {
 	"DS:intr:COUNTER:15:0:U "
 	"DS:ctxt:COUNTER:15:0:U "
 	"DS:fork:COUNTER:15:0:U "
 };
 
-static char * get_ds(int ds_id)
+static const char * get_ds(int ds_id)
 {
 	switch (ds_id) {
 	case DS_CPU:
@@ -104,10 +104,10 @@ static int probe(void)
 
 			else if (numfields == 5)
 				val[5] = val[6] = val[7] = val[8] = "0";
-				
+
 			else if (numfields == 8)
 				val[8] = "0";
-			
+
 			probe_submit(&plugin, filename, DS_CPU,
 					"%s:%s:%s:%s:%s:%s:%s:%s",
 					val[1], val[2], val[3], val[4],
diff --git a/p_uptime.c b/p_uptime.c
index 86a13a7..11344c3 100644
--- a/p_uptime.c
+++ b/p_uptime.c
@@ -25,12 +25,12 @@
 
 struct sammler_plugin plugin;
 
-static char *ds_def = {
+static const char *ds_def = {
 	"DS:uptime:GAUGE:15:0:U "
 	"DS:idletime:GAUGE:15:0:U "
 };
 
-static char * get_ds(int ds_id)
+static const char * get_ds(int ds_id)
 {
 	return ds_def;
 }
diff --git a/p_vmstat.c b/p_vmstat.c
index f9fc46e..33e81d0 100644
--- a/p_vmstat.c
+++ b/p_vmstat.c
@@ -27,7 +27,7 @@
 
 struct sammler_plugin plugin;
 
-static char *ds_def = {
+static const char *ds_def = {
 	"DS:pgalloc_high:DERIVE:15:0:U "
 	"DS:pgalloc_normal:DERIVE:15:0:U "
 	"DS:pgalloc_dma:DERIVE:15:0:U "
@@ -35,7 +35,7 @@ static char *ds_def = {
 	"DS:pgfault:DERIVE:15:0:U "
 };
 
-static char * get_ds(int ds_id)
+static const char * get_ds(int ds_id)
 {
 	return ds_def;
 }
diff --git a/plugins.c b/plugins.c
index 1f98ce3..76ec02d 100644
--- a/plugins.c
+++ b/plugins.c
@@ -24,6 +24,7 @@
 #include <stdlib.h>
 #include <stdarg.h>
 #include <time.h>
+#include <limits.h>
 
 #include "list.h"
 
@@ -51,14 +52,14 @@ static int plugin_init_cb(const char *filename, void *privdata)
 	if (plugin_dir == NULL)
 		plugin_dir = config_get_string("global", "plugin_dir", ".");
 
-	buffer = malloc(BUFSIZE);
+	buffer = malloc(PATH_MAX);
 	if (buffer == NULL) {
 		log_print(LOG_ERROR, "plugin_load: out of memory");
 		return -1;
 	}
 
-	len = snprintf(buffer, BUFSIZE, "%s/%s", plugin_dir, filename);
-	if (len < 0 || len >= BUFSIZE) {
+	len = snprintf(buffer, PATH_MAX, "%s/%s", plugin_dir, filename);
+	if (len < 0 || len >= PATH_MAX) {
 		log_print(LOG_ERROR, "plugin_load: file name too long: %s/%s", plugin_dir, filename);
 		free(buffer);
 		return -1;
@@ -117,7 +118,7 @@ void plugins_probe(void)
 		net_submit_flush();
 }
 
-struct sammler_plugin * plugin_lookup(char *name)
+struct sammler_plugin * plugin_lookup(const char *name)
 {
 	struct sammler_plugin *plugin;
 	list_for_each_entry(plugin, &plugin_list, list) {
@@ -128,7 +129,7 @@ struct sammler_plugin * plugin_lookup(char *name)
 	return NULL;
 }
 
-int probe_submit(struct sammler_plugin *plugin, char *filename, int ds_id, const char *fmt, ... )
+int probe_submit(struct sammler_plugin *plugin, const char *filename, int ds_id, const char *fmt, ... )
 {
 	static const char *hostname = NULL;
 
diff --git a/plugins.h b/plugins.h
index 0193fa7..900e2cd 100644
--- a/plugins.h
+++ b/plugins.h
@@ -9,21 +9,21 @@
 
 struct sammler_plugin {
 	struct list_head list;
-	char *name;
+	const char *name;
 	unsigned int interval;
 	unsigned long lastprobe;
 	int (*init) (void);
 	int (*fini) (void);
 	int (*probe) (void);
-	char * (*get_ds) (int ds_id);
+	const char * (*get_ds) (int ds_id);
 };
 
 void plugin_init(int flags);
 
 void plugins_probe(void);
 
-struct sammler_plugin * plugin_lookup(char *name);
+struct sammler_plugin * plugin_lookup(const char *name);
 
-int probe_submit(struct sammler_plugin *plugin, char *filename, int ds_id, const char *fmt, ... );
+int probe_submit(struct sammler_plugin *plugin, const char *filename, int ds_id, const char *fmt, ... );
 
 #endif /* _PLUGINS_H_ */
diff --git a/rrdtool.c b/rrdtool.c
index 5e0ca37..bd0d702 100644
--- a/rrdtool.c
+++ b/rrdtool.c
@@ -73,7 +73,7 @@ static int append_rra_config(char *buffer, int size, int *pos)
 	return config_get_strings("global", "rra", append_rra_config_cb, &data);
 }
 
-static int do_rrd(int mode, char *cmd)
+static int do_rrd(int mode, const char *cmd)
 {
 	int argc;
 	char *argv[ARGCMAX];
@@ -103,11 +103,12 @@ static int do_rrd(int mode, char *cmd)
 	return 0;
 }
 
-static int rrd_create_file(char *filename, char *plugin_name, int ds_id)
+static int rrd_create_file(const char *filename, const char *plugin_name, int ds_id)
 {
 	struct sammler_plugin *plugin;
 	int pos, step, retval;
-	char *ds_def, *buffer;
+	const char *ds_def;
+	char *buffer;
 
 	plugin = plugin_lookup(plugin_name);
 	if (plugin == NULL) {
@@ -147,7 +148,7 @@ static int rrd_create_file(char *filename, char *plugin_name, int ds_id)
 	return retval;
 }
 
-static int rrd_update_file(char *filename, char *values)
+static int rrd_update_file(const char *filename, const char *values)
 {
 	int pos, retval;
 	char *buffer;
@@ -171,7 +172,7 @@ static int rrd_update_file(char *filename, char *values)
 	return retval;
 }
 
-static int check_create_dir(char *dir)
+static int check_create_dir(const char *dir)
 {
 	struct stat statbuf;
 	if (stat(dir, &statbuf) == -1) {
@@ -228,7 +229,7 @@ static int create_parent_dirs(char *filename)
 	return 0;
 }
 
-int rrd_submit(const char *hostname, char *plugin, char *filename, int ds_id, char *data)
+int rrd_submit(const char *hostname, const char *plugin, const char *filename, int ds_id, const char *data)
 {
 	struct stat statbuf;
 	static const char *rrd_dir = NULL;
diff --git a/rrdtool.h b/rrdtool.h
index 6af78e6..ce15c5a 100644
--- a/rrdtool.h
+++ b/rrdtool.h
@@ -2,7 +2,7 @@
 #define _RRDTOOL_H_
 
 #ifdef WITH_RRD
-int rrd_submit(const char *hostname, char *plugin, char *filename, int ds_id, char *data);
+int rrd_submit(const char *hostname, const char *plugin, const char *filename, int ds_id, const char *data);
 #else
 #define rrd_submit(hostname, plugin, filename, ds_id, data)
 #endif