diff --git a/file.c b/file.c
index 9704cea9b..655cce42f 100644
--- a/file.c
+++ b/file.c
@@ -449,7 +449,7 @@ check_command(char *cmd, int auxbin_p)
 }
 
 char *
-acceptableEncoding()
+acceptableEncoding(void)
 {
     static Str encodings = NULL;
     struct compression_decoder *d;
@@ -5547,7 +5547,7 @@ HTMLtagproc1(struct parsed_tag *tag, struct html_feed_environ *h_env)
 static TextLineListItem *_tl_lp2;
 
 static Str
-textlist_feed()
+textlist_feed(void)
 {
     TextLine *p;
     if (_tl_lp2 != NULL) {
@@ -6330,7 +6330,7 @@ HTMLlineproc2(Buffer *buf, TextLineList *tl)
 static InputStream _file_lp2;
 
 static Str
-file_feed()
+file_feed(void)
 {
     Str s;
     s = StrISgets(_file_lp2);
diff --git a/history.c b/history.c
index 2ba0400d1..6a993c43f 100644
--- a/history.c
+++ b/history.c
@@ -89,7 +89,7 @@ saveHistory(Hist *hist, size_t size)
 #endif				/* USE_HISTORY */
 
 Hist *
-newHist()
+newHist(void)
 {
     Hist *hist;
 
diff --git a/history.h b/history.h
index e2b3bf2cc..a6468eca6 100644
--- a/history.h
+++ b/history.h
@@ -18,7 +18,7 @@ typedef struct {
     Hash_sv *hash;
 } Hist;
 
-extern Hist *newHist();
+extern Hist *newHist(void);
 extern Hist *copyHist(Hist *hist);
 extern HistItem *unshiftHist(Hist *hist, char *ptr);
 extern HistItem *pushHist(Hist *hist, char *ptr);
diff --git a/indep.c b/indep.c
index 4d13a3fe4..d9b9ae9ff 100644
--- a/indep.c
+++ b/indep.c
@@ -840,32 +840,32 @@ w3m_dir(const char *name, char *dft)
 }
 
 char *
-w3m_auxbin_dir()
+w3m_auxbin_dir(void)
 {
     return w3m_dir("W3M_AUXBIN_DIR", AUXBIN_DIR);
 }
 
 char *
-w3m_lib_dir()
+w3m_lib_dir(void)
 {
     /* FIXME: use W3M_CGIBIN_DIR? */
     return w3m_dir("W3M_LIB_DIR", CGIBIN_DIR);
 }
 
 char *
-w3m_etc_dir()
+w3m_etc_dir(void)
 {
     return w3m_dir("W3M_ETC_DIR", ETC_DIR);
 }
 
 char *
-w3m_conf_dir()
+w3m_conf_dir(void)
 {
     return w3m_dir("W3M_CONF_DIR", CONF_DIR);
 }
 
 char *
-w3m_help_dir()
+w3m_help_dir(void)
 {
     return w3m_dir("W3M_HELP_DIR", HELP_DIR);
 }
diff --git a/indep.h b/indep.h
index b123c8542..d4bef53c2 100644
--- a/indep.h
+++ b/indep.h
@@ -86,11 +86,11 @@ extern void growbuf_reserve(struct growbuf *gb, int leastarea);
 extern void growbuf_append(struct growbuf *gb, const unsigned char *src, int len);
 #define GROWBUF_ADD_CHAR(gb,ch) ((((gb)->length>=(gb)->area_size)?growbuf_reserve(gb,(gb)->length+1):(void)0),(void)((gb)->ptr[(gb)->length++] = (ch)))
 
-extern char *w3m_auxbin_dir();
-extern char *w3m_lib_dir();
-extern char *w3m_etc_dir();
-extern char *w3m_conf_dir();
-extern char *w3m_help_dir();
+extern char *w3m_auxbin_dir(void);
+extern char *w3m_lib_dir(void);
+extern char *w3m_etc_dir(void);
+extern char *w3m_conf_dir(void);
+extern char *w3m_help_dir(void);
 
 #define NewWithoutGC(type)	((type*)xmalloc(sizeof(type)))
 #define NewWithoutGC_N(type,n)	((type*)xmalloc((n)*sizeof(type)))
diff --git a/mailcap.c b/mailcap.c
index f0c624288..c0275eeb5 100644
--- a/mailcap.c
+++ b/mailcap.c
@@ -220,7 +220,7 @@ loadMailcap(char *filename)
 }
 
 void
-initMailcap()
+initMailcap(void)
 {
     TextListItem *tl;
     int i;
@@ -238,7 +238,7 @@ initMailcap()
 }
 
 char *
-acceptableMimeTypes()
+acceptableMimeTypes(void)
 {
     static Str types = NULL;
     TextList *l;
diff --git a/proto.h b/proto.h
index be9d64af0..3be7d225b 100644
--- a/proto.h
+++ b/proto.h
@@ -164,7 +164,7 @@ extern int currentLn(Buffer *buf);
 extern void tmpClearBuffer(Buffer *buf);
 extern char *filename_extension(char *patch, int is_url);
 #ifdef USE_EXTERNAL_URI_LOADER
-extern void initURIMethods();
+extern void initURIMethods(void);
 extern Str searchURIMethods(ParsedURL *pu);
 extern void chkExternalURIBuffer(Buffer *buf);
 #endif
@@ -188,7 +188,7 @@ extern char *url_decode0(const char *url);
 #define url_decode2(url, buf) url_decode0(url)
 #endif /* !defined(USE_M17N) */
 extern void examineFile(char *path, URLFile *uf);
-extern char *acceptableEncoding();
+extern char *acceptableEncoding(void);
 extern int dir_exist(char *path);
 extern int is_html_type(char *type);
 #ifdef USE_M17N
@@ -533,10 +533,10 @@ extern char getch(void);
 extern void bell(void);
 extern int sleep_till_anykey(int sec, int purge);
 #ifdef USE_IMAGE
-extern void touch_cursor();
+extern void touch_cursor(void);
 #endif
-extern void initMimeTypes();
-extern void free_ssl_ctx();
+extern void initMimeTypes(void);
+extern void free_ssl_ctx(void);
 extern ParsedURL *baseURL(Buffer *buf);
 extern int openSocket(char *hostname, char *remoteport_name,
 		      unsigned short remoteport_num);
@@ -555,8 +555,8 @@ extern URLFile openURL(char *url, ParsedURL *pu, ParsedURL *current,
 		       HRequest *hr, unsigned char *status);
 extern int mailcapMatch(struct mailcap *mcap, char *type);
 extern struct mailcap *searchMailcap(struct mailcap *table, char *type);
-extern void initMailcap();
-extern char *acceptableMimeTypes();
+extern void initMailcap(void);
+extern char *acceptableMimeTypes(void);
 extern struct mailcap *searchExtViewer(char *type);
 extern Str unquote_mailcap(char *qstr, char *type, char *name, char *attr,
 			   int *mc_stat);
diff --git a/rc.c b/rc.c
index 9fb08fb4d..ba8f9ee47 100644
--- a/rc.c
+++ b/rc.c
@@ -1180,8 +1180,8 @@ interpret_rc(FILE * f)
     }
 }
 
-void
-parse_proxy()
+static void
+parse_proxy(void)
 {
     if (non_null(HTTP_proxy))
 	parseURL(HTTP_proxy, &HTTP_proxy_parsed, NULL);
@@ -1200,8 +1200,8 @@ parse_proxy()
 }
 
 #ifdef USE_COOKIE
-void
-parse_cookie()
+static void
+parse_cookie(void)
 {
     if (non_null(cookie_reject_domains))
 	Cookie_reject_domains = make_domain_list(cookie_reject_domains);
diff --git a/terms.c b/terms.c
index e272aab93..253f39ea2 100644
--- a/terms.c
+++ b/terms.c
@@ -41,7 +41,7 @@ static int xpix, ypix, nbs, obs = 0;
 
 static int is_xterm = 0;
 
-void mouse_init(), mouse_end();
+void mouse_init(void), mouse_end(void);
 int mouseActive = 0;
 #endif				/* USE_MOUSE */
 
@@ -263,7 +263,7 @@ check_cygwin_console(void)
 char *getenv(const char *);
 MySignalHandler reset_exit(SIGNAL_ARG), reset_error_exit(SIGNAL_ARG), error_dump(SIGNAL_ARG);
 void setlinescols(void);
-void flush_tty();
+void flush_tty(void);
 
 #ifndef SIGIOT
 #define SIGIOT SIGABRT
@@ -452,7 +452,7 @@ extern int tgetflag(char *);
 extern char *tgetstr(char *, char **);
 extern char *tgoto(char *, int, int);
 extern int tputs(char *, int, int (*)(char));
-void clear(), wrap(), touch_line(), touch_column(int);
+void clear(void), wrap(void), touch_line(void), touch_column(int);
 #if 0
 void need_clrtoeol(void);
 #endif
@@ -2654,7 +2654,7 @@ mouse_inactive()
 #endif				/* USE_MOUSE */
 
 void
-flush_tty()
+flush_tty(void)
 {
     if (ttyf)
 	fflush(ttyf);
@@ -2662,7 +2662,7 @@ flush_tty()
 
 #ifdef USE_IMAGE
 void
-touch_cursor()
+touch_cursor(void)
 {
 #ifdef USE_M17N
     int i;
diff --git a/url.c b/url.c
index 07f3ea09c..b4c9ce450 100644
--- a/url.c
+++ b/url.c
@@ -202,7 +202,7 @@ loadMimeTypes(char *filename)
 }
 
 void
-initMimeTypes()
+initMimeTypes(void)
 {
     int i;
     TextListItem *tl;
@@ -251,7 +251,7 @@ KeyAbort(SIGNAL_ARG)
 SSL_CTX *ssl_ctx = NULL;
 
 void
-free_ssl_ctx()
+free_ssl_ctx(void)
 {
     if (ssl_ctx != NULL)
 	SSL_CTX_free(ssl_ctx);
@@ -262,7 +262,7 @@ free_ssl_ctx()
 #if SSLEAY_VERSION_NUMBER >= 0x00905100
 #include <openssl/rand.h>
 static void
-init_PRNG()
+init_PRNG(void)
 {
     char buffer[256];
     const char *file;
@@ -2305,7 +2305,7 @@ loadURIMethods(char *filename)
 }
 
 void
-initURIMethods()
+initURIMethods(void)
 {
     TextList *methodmap_list = NULL;
     TextListItem *tl;