diff --git a/plugins/python/python.c b/plugins/python/python.c
index 1904a3e9..0ce6ad6e 100644
--- a/plugins/python/python.c
+++ b/plugins/python/python.c
@@ -414,6 +414,9 @@ Util_BuildEOLList(char *word[])
 	PyObject *list;
 	int listsize = 31;
 	int i;
+	char *accum = NULL;
+	char *last = NULL;
+
 	/* Find the last valid array member; there may be intermediate NULLs that
 	 * would otherwise cause us to drop some members. */
 	while (listsize > 0 &&
@@ -424,10 +427,9 @@ Util_BuildEOLList(char *word[])
 		PyErr_Print();
 		return NULL;
 	}
-	char *accum = NULL;
-	char *last = NULL;
 	for (i = listsize; i > 0; i--) {
 		char *part = word[i];
+		PyObject *uni_part;
 		if (accum == NULL) {
 			accum = g_strdup (part);
 		} else if (part != NULL && part[0] != 0) {
@@ -443,7 +445,7 @@ Util_BuildEOLList(char *word[])
 				return NULL;
 			}
 		}
-		PyObject *uni_part = PyUnicode_FromString(accum);
+		uni_part = PyUnicode_FromString(accum);
 		PyList_SetItem(list, i - 1, uni_part);
 	}
 
diff --git a/plugins/sysinfo/hwmon.c b/plugins/sysinfo/hwmon.c
index 389244ac..e562458f 100644
--- a/plugins/sysinfo/hwmon.c
+++ b/plugins/sysinfo/hwmon.c
@@ -53,8 +53,9 @@ void get_hwmon_chip_name(char *name)
 void get_hwmon_temp(unsigned int *value, unsigned int *sensor)
 {
 	char buffer[bsize];
+	FILE *fp;
 	snprintf(buffer, bsize, "/sys/class/hwmon/hwmon0/device/temp%i_input", *sensor);
-	FILE *fp = fopen(buffer, "r");
+	fp = fopen(buffer, "r");
 	if(fp != NULL) {
 		if(fgets(buffer, bsize, fp) != NULL)
 			*value = atoi(buffer);
diff --git a/plugins/sysinfo/match.c b/plugins/sysinfo/match.c
index adfbff1b..f8a8cf96 100644
--- a/plugins/sysinfo/match.c
+++ b/plugins/sysinfo/match.c
@@ -32,12 +32,12 @@ float percentage(unsigned long long *free, unsigned long long *total)
 
 char *pretty_freespace(const char *desc, unsigned long long *free_k, unsigned long long *total_k)
 {
-        char *result, **quantity;
+	char *quantities[] = { "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB", 0 };
+	char *result, **quantity;
 	double free_space, total_space;
 	free_space = *free_k;
 	total_space = *total_k;
         result = malloc(bsize * sizeof(char));
-	char *quantities[] = { "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB", 0 };
 	if (total_space == 0)
 	{
 		snprintf(result, bsize, "%s: none", desc);
diff --git a/plugins/sysinfo/parse.c b/plugins/sysinfo/parse.c
index 4c15897a..3f1ad6c5 100644
--- a/plugins/sysinfo/parse.c
+++ b/plugins/sysinfo/parse.c
@@ -34,6 +34,7 @@
 #include "match.h"
 #include "hwmon.h"
 #include "xsys.h"
+#include "parse.h"
 
 int xs_parse_cpu(char *model, char *vendor, double *freq, char *cache, unsigned int *count)
 {
diff --git a/plugins/sysinfo/pci.c b/plugins/sysinfo/pci.c
index bc8fb11f..9946c446 100644
--- a/plugins/sysinfo/pci.c
+++ b/plugins/sysinfo/pci.c
@@ -115,9 +115,10 @@ void pci_find_fullname(char *fullname, char *vendor, char *device)
 	char devicename[bsize/2] = "";
 	char *position;
 	int cardfound = 0;
+	FILE *fp;
 
 	sysinfo_get_pciids (buffer);
-	FILE *fp = fopen (buffer, "r");
+	fp = fopen (buffer, "r");
 
 	if(fp == NULL) {
 		snprintf(fullname, bsize, "%s:%s", vendor, device);
diff --git a/plugins/sysinfo/xsys.c b/plugins/sysinfo/xsys.c
index 4ab6e873..79abcea1 100644
--- a/plugins/sysinfo/xsys.c
+++ b/plugins/sysinfo/xsys.c
@@ -878,11 +878,11 @@ sysinfo_cb (char *word[], char *word_eol[], void *userdata)
 int
 hexchat_plugin_init (hexchat_plugin *plugin_handle, char **plugin_name, char **plugin_desc, char **plugin_version, char *arg)
 {
+	char buffer[bsize];
 	ph = plugin_handle;
 	*plugin_name    = name;
 	*plugin_desc    = desc;
 	*plugin_version = version;
-	char buffer[bsize];
 
 	hexchat_hook_command (ph, "SYSINFO",	HEXCHAT_PRI_NORM,	sysinfo_cb,	sysinfo_help, NULL);
 	hexchat_hook_command (ph, "NETDATA",	HEXCHAT_PRI_NORM,	netdata_cb,	NULL, NULL);
diff --git a/src/common/cfgfiles.c b/src/common/cfgfiles.c
index 71a5bf96..735bbfe2 100644
--- a/src/common/cfgfiles.c
+++ b/src/common/cfgfiles.c
@@ -1311,7 +1311,7 @@ cmd_set (struct session *sess, char *tbuf, char *word[], char *word_eol[])
 }
 
 int
-hexchat_open_file (char *file, int flags, int mode, int xof_flags)
+hexchat_open_file (const char *file, int flags, int mode, int xof_flags)
 {
 	char *buf;
 	int fd;
diff --git a/src/common/cfgfiles.h b/src/common/cfgfiles.h
index 8b996ca0..c460ce60 100644
--- a/src/common/cfgfiles.h
+++ b/src/common/cfgfiles.h
@@ -48,7 +48,7 @@ void list_loadconf (char *file, GSList ** list, char *defaultconf);
 int list_delentry (GSList ** list, char *name);
 void list_addentry (GSList ** list, char *cmd, char *name);
 int cmd_set (session *sess, char *tbuf, char *word[], char *word_eol[]);
-int hexchat_open_file (char *file, int flags, int mode, int xof_flags);
+int hexchat_open_file (const char *file, int flags, int mode, int xof_flags);
 FILE *hexchat_fopen_file (const char *file, const char *mode, int xof_flags);
 
 #define XOF_DOMODE 1
diff --git a/src/common/dbus/dbus-plugin.c b/src/common/dbus/dbus-plugin.c
index ee8accfe..bb9fb5e1 100644
--- a/src/common/dbus/dbus-plugin.c
+++ b/src/common/dbus/dbus-plugin.c
@@ -26,6 +26,7 @@
 #include <dbus/dbus-glib-lowlevel.h>
 #include <glib/gi18n.h>
 #include "hexchat-plugin.h"
+#include "dbus-plugin.h"
 
 #define PNAME _("remote access")
 #define PDESC _("plugin for remote access using DBUS")
diff --git a/src/common/dbus/example.c b/src/common/dbus/example.c
index c3ad4ff3..0228b884 100644
--- a/src/common/dbus/example.c
+++ b/src/common/dbus/example.c
@@ -33,7 +33,7 @@ guint command_id;
 guint server_id;
 
 static void
-write_error (char *message,
+write_error (const char *message,
 	     GError **error)
 {
 	if (error == NULL || *error == NULL) {
diff --git a/src/common/make-te.c b/src/common/make-te.c
index 309eec2f..5eceb5f0 100644
--- a/src/common/make-te.c
+++ b/src/common/make-te.c
@@ -42,7 +42,7 @@
 #include <string.h>
 #include <stdlib.h>
 
-int main()
+int main(void)
 {
 	char name[512];
 	char num[512];
diff --git a/src/common/url.c b/src/common/url.c
index 1321374f..5fbeb6c8 100644
--- a/src/common/url.c
+++ b/src/common/url.c
@@ -429,7 +429,7 @@ regex_match (const GRegex *re, const char *word, int *start, int *end)
 #define OPT_PORT "(" PORT ")?"
 
 static GRegex *
-make_re (char *grist)
+make_re (const char *grist)
 {
 	GRegex *ret;
 	GError *err = NULL;
diff --git a/src/common/util.c b/src/common/util.c
index b5ee1af2..a6c4fad8 100644
--- a/src/common/util.c
+++ b/src/common/util.c
@@ -1526,7 +1526,7 @@ canonalize_key (char *key)
 }
 
 int
-portable_mode ()
+portable_mode (void)
 {
 #ifdef WIN32
 	if ((_access( "portable-mode", 0 )) != -1)
@@ -1543,7 +1543,7 @@ portable_mode ()
 }
 
 int
-unity_mode ()
+unity_mode (void)
 {
 #ifdef G_OS_UNIX
 	const char *env = g_getenv("XDG_CURRENT_DESKTOP");
diff --git a/src/common/util.h b/src/common/util.h
index 5231e56d..8b2762fb 100644
--- a/src/common/util.h
+++ b/src/common/util.h
@@ -73,8 +73,8 @@ guint32 str_hash (const char *key);
 guint32 str_ihash (const unsigned char *key);
 void safe_strcpy (char *dest, const char *src, int bytes_left);
 void canonalize_key (char *key);
-int portable_mode ();
-int unity_mode ();
+int portable_mode (void);
+int unity_mode (void);
 char *encode_sasl_pass_plain (char *user, char *pass);
 char *encode_sasl_pass_blowfish (char *user, char *pass, char *data);
 char *encode_sasl_pass_aes (char *user, char *pass, char *data);
diff --git a/src/fe-gtk/chanview-tabs.c b/src/fe-gtk/chanview-tabs.c
index 8f940c24..32039d6d 100644
--- a/src/fe-gtk/chanview-tabs.c
+++ b/src/fe-gtk/chanview-tabs.c
@@ -62,12 +62,13 @@ cv_tabs_sizerequest (GtkWidget *viewport, GtkRequisition *requisition, chanview
 static void
 cv_tabs_sizealloc (GtkWidget *widget, GtkAllocation *allocation, chanview *cv)
 {
+	GdkWindow *parent_win;
 	GtkAdjustment *adj;
 	GtkWidget *inner;
 	gint viewport_size;
 
 	inner = ((tabview *)cv)->inner;
-	GdkWindow *parent_win = gtk_widget_get_window (gtk_widget_get_parent (inner));
+	parent_win = gtk_widget_get_window (gtk_widget_get_parent (inner));
 
 	if (cv->vertical)
 	{
diff --git a/src/fe-gtk/plugin-tray.c b/src/fe-gtk/plugin-tray.c
index b3e34c0a..3cd6502d 100644
--- a/src/fe-gtk/plugin-tray.c
+++ b/src/fe-gtk/plugin-tray.c
@@ -186,9 +186,10 @@ fe_tray_set_balloon (const char *title, const char *text)
 
 	if (!notify_is_initted())
 	{
+		GList* server_caps;
 		notify_init(PACKAGE_NAME);
 
-		GList* server_caps = notify_get_server_caps ();
+		server_caps = notify_get_server_caps ();
 		if (g_list_find_custom (server_caps, "body-markup", (GCompareFunc)strcmp))
 		{
 			notify_text_strip_flags |= STRIP_ESCMARKUP;
diff --git a/src/fe-gtk/xtext.c b/src/fe-gtk/xtext.c
index 7b0e64c6..63b87ce8 100644
--- a/src/fe-gtk/xtext.c
+++ b/src/fe-gtk/xtext.c
@@ -3257,7 +3257,7 @@ gtk_xtext_render_stamp (GtkXText * xtext, textentry * ent,
 {
 	textentry tmp_ent;
 	int jo, ji, hs;
-	int xsize, y;
+	int xsize, y, emphasis;
 
 	/* trashing ent here, so make a backup first */
 	memcpy (&tmp_ent, ent, sizeof (tmp_ent));
@@ -3267,7 +3267,7 @@ gtk_xtext_render_stamp (GtkXText * xtext, textentry * ent,
 	xtext->jump_out_offset = 0;
 	xtext->jump_in_offset = 0;
 	xtext->hilight_start = 0xffff;	/* temp disable */
-	int emphasis = 0;
+	emphasis = 0;
 
 	if (xtext->mark_stamp)
 	{