diff --git a/utils/set.c b/utils/set.c
index fade49fe..769cdaca 100644
--- a/utils/set.c
+++ b/utils/set.c
@@ -98,7 +98,7 @@ SetNoisyInt(parm,valueS,file)
 int
 SetNoisyBool(parm,valueS,file)
     bool *parm;
-    char *valueS;
+    const char *valueS;
     FILE *file;
 {
     int n, which, result = -2;
diff --git a/utils/utils.h b/utils/utils.h
index 52d4f484..846507f8 100644
--- a/utils/utils.h
+++ b/utils/utils.h
@@ -84,7 +84,7 @@ extern gzFile PaLockZOpen(const char *file, const char *mode, const char *ext, c
 extern char *PaCheckCompressed(const char *filename);
 #endif
 
-extern int SetNoisyBool(bool *, char *, FILE *);
+extern int SetNoisyBool(bool *parm, const char *valueS, FILE *file);
 
 #ifdef FILE_LOCKS
 extern FILE *flock_open();