diff --git a/src/utils.c b/src/utils.c
index e155c3b..d4f0618 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -199,7 +199,7 @@ char *game_filename (int gamenum)
 /***********************************************************************/
 // err_exit: Print an error and exit
 
-void err_exit (const char *format, ...)
+void err_exit (const char *restrict format, ...)
 {
     va_list args;
 
@@ -219,7 +219,7 @@ void err_exit (const char *format, ...)
 /***********************************************************************/
 // errno_exit: Print an error message (using errno) and exit
 
-void errno_exit (const char *format, ...)
+void errno_exit (const char *restrict format, ...)
 {
     va_list args;
     int saved_errno = errno;
@@ -399,7 +399,7 @@ ssize_t l_strfmon (char *restrict s, size_t maxsize,
 /***********************************************************************/
 // scramble: Scramble (encrypt) the buffer
 
-char *scramble (int key, char *buf, int bufsize)
+char *scramble (int key, char *restrict buf, int bufsize)
 {
     /* The algorithm used here is reversable: scramble(scramble(...))
        will (or, at least, should!) return the same as the original
@@ -410,9 +410,8 @@ char *scramble (int key, char *buf, int bufsize)
     if (buf != NULL && key != 0) {
 	char *p = buf;
 	unsigned char k = ~key;
-	int i;
 
-	for (i = 0; i < bufsize && *p != '\0'; i++, k++, p++) {
+	for (int i = 0; i < bufsize && *p != '\0'; i++, k++, p++) {
 	    char c = *p;
 	    char r = c ^ k;	// Simple encryption: XOR on a moving key
 
@@ -430,7 +429,7 @@ char *scramble (int key, char *buf, int bufsize)
 /***********************************************************************/
 // unscramble: Unscramble (decrypt) the buffer
 
-char *unscramble (int key, char *buf, int bufsize)
+char *unscramble (int key, char *restrict buf, int bufsize)
 {
     return scramble(key, buf, bufsize);
 }
diff --git a/src/utils.h b/src/utils.h
index 1c0eb9e..ec87e80 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -142,7 +142,7 @@ extern char *game_filename (int gamenum);
   with the user string as a second argument), NOT passed in as the format
   itself.
 */
-extern void err_exit (const char *format, ...)
+extern void err_exit (const char *restrict format, ...)
     __attribute__((noreturn, format (printf, 1, 2)));
 
 
@@ -161,7 +161,7 @@ extern void err_exit (const char *format, ...)
   colons nor the trailing end-line character.  The format may be NULL if
   no intermediate message is needed.
 */
-extern void errno_exit (const char *format, ...)
+extern void errno_exit (const char *restrict format, ...)
     __attribute__((noreturn, format (printf, 1, 2)));
 
 
@@ -278,7 +278,7 @@ extern ssize_t l_strfmon (char *restrict s, size_t maxsize,
   and after encryption.  At most bufsize bytes are encrypted; buf is
   returned as the result.
 */
-extern char *scramble (int key, char *buf, int bufsize);
+extern char *scramble (int key, char *restrict buf, int bufsize);
 
 
 /*
@@ -297,7 +297,7 @@ extern char *scramble (int key, char *buf, int bufsize);
   will any encrypted character map back to these values).  At most
   bufsize bytes are decrypted; buf is returned as the result.
 */
-extern char *unscramble (int key, char *buf, int bufsize);
+extern char *unscramble (int key, char *restrict buf, int bufsize);
 
 
 #endif /* included_UTILS_H */