diff --git a/src/util/error.c b/src/util/error.c
index 05e42a2cd..b8e58344c 100644
--- a/src/util/error.c
+++ b/src/util/error.c
@@ -38,7 +38,7 @@
 char full_static_version[1024] = "ELinks " VERSION_STRING;
 
 static void
-er(int bell, int shall_sleep, char *fmt, va_list params)
+er(int bell, int shall_sleep, const char *fmt, va_list params)
 {
 	if (bell)
 #ifdef CONFIG_OS_WIN32
@@ -56,7 +56,7 @@ int errline;
 const char *errfile;
 
 void
-elinks_debug(char *fmt, ...)
+elinks_debug(const char *fmt, ...)
 {
 	char errbuf[4096];
 	va_list params;
@@ -72,7 +72,7 @@ elinks_debug(char *fmt, ...)
 }
 
 void
-elinks_wdebug(char *fmt, ...)
+elinks_wdebug(const char *fmt, ...)
 {
 	char errbuf[4096];
 	va_list params;
@@ -88,7 +88,7 @@ elinks_wdebug(char *fmt, ...)
 }
 
 void
-elinks_error(char *fmt, ...)
+elinks_error(const char *fmt, ...)
 {
 	char errbuf[4096];
 	va_list params;
@@ -104,7 +104,7 @@ elinks_error(char *fmt, ...)
 }
 
 void
-elinks_internal(char *fmt, ...)
+elinks_internal(const char *fmt, ...)
 {
 	char errbuf[4096];
 	va_list params;
@@ -125,7 +125,7 @@ elinks_internal(char *fmt, ...)
 
 
 void
-usrerror(char *fmt, ...)
+usrerror(const char *fmt, ...)
 {
 	va_list params;
 
@@ -143,7 +143,7 @@ usrerror(char *fmt, ...)
 int assert_failed = 0;
 
 void
-elinks_assertm(int x, char *fmt, ...)
+elinks_assertm(int x, const char *fmt, ...)
 {
 	char *buf = NULL;
 	va_list params;
@@ -201,7 +201,7 @@ done_log(void)
 
 void
 elinks_log(char *msg, char *file, int line,
-	   char *fmt, ...)
+	   const char *fmt, ...)
 {
 	static char *log_files = NULL;
 	static char *log_msg = NULL;
diff --git a/src/util/error.h b/src/util/error.h
index 0c2c3a00d..790cee006 100644
--- a/src/util/error.h
+++ b/src/util/error.h
@@ -23,7 +23,7 @@ extern const char *errfile;
  * lying there commented out, as it may get handy). */
 #undef DBG
 #define DBG errfile = __FILE__, errline = __LINE__, elinks_debug
-void elinks_debug(char *fmt, ...);
+void elinks_debug(const char *fmt, ...);
 
 /** @c WDBG(format_string) is used for printing of debugging information, akin
  * to DBG(). However, it sleep(1)s, therefore being useful when it is going
@@ -32,7 +32,7 @@ void elinks_debug(char *fmt, ...);
  * handy). */
 #undef WDBG
 #define WDBG errfile = __FILE__, errline = __LINE__, elinks_wdebug
-void elinks_wdebug(char *fmt, ...);
+void elinks_wdebug(const char *fmt, ...);
 
 /** @c ERROR(format_string) is used to report non-fatal unexpected errors during
  * the ELinks run. It tries to (not that agressively) draw user's attention to
@@ -42,20 +42,20 @@ void elinks_wdebug(char *fmt, ...);
  * this kind of stuff, and there's nothing naughty about using that. */
 #undef ERROR
 #define ERROR errfile = __FILE__, errline = __LINE__, elinks_error
-void elinks_error(char *fmt, ...);
+void elinks_error(const char *fmt, ...);
 
 /** @c INTERNAL(format_string) is used to report fatal errors during the ELinks
  * run. It tries to draw user's attention to the error and dumps core if ELinks
  * is running in the CONFIG_DEBUG mode. */
 #undef INTERNAL
 #define INTERNAL errfile = __FILE__, errline = __LINE__, elinks_internal
-void elinks_internal(char *fmt, ...);
+void elinks_internal(const char *fmt, ...);
 
 
 /** @c usrerror(format_string) is used to report user errors during a peaceful
  * ELinks run. It does not belong to the family above - it doesn't print code
  * location, beep nor sleep, it just wraps around fprintf(stderr, "...\n");. */
-void usrerror(char *fmt, ...);
+void usrerror(const char *fmt, ...);
 
 
 #ifdef HAVE_VARIADIC_MACROS
@@ -75,7 +75,7 @@ void usrerror(char *fmt, ...);
  */
 void
 elinks_log(char *msg, char *file, int line,
-	   char *fmt, ...);
+	   const char *fmt, ...);
 
 #undef LOG_ERR
 #define LOG_ERR(args...) \
@@ -147,7 +147,7 @@ do { if (!assert_failed && (assert_failed = !(x))) { \
 #ifdef CONFIG_FASTMEM
 static inline
 #endif
-void elinks_assertm(int x, char *fmt, ...)
+void elinks_assertm(int x, const char *fmt, ...)
 #ifdef CONFIG_FASTMEM
 {
 	/* We don't do anything in CONFIG_FASTMEM mode. Let's hope that the compiler