diff --git a/src/files.c b/src/files.c
index 1d9e08fb..55e7939d 100644
--- a/src/files.c
+++ b/src/files.c
@@ -250,7 +250,7 @@ int do_lockfile(const char *filename)
     char *lockbase = basename((char *) mallocstrcpy(NULL, filename));
     ssize_t lockfilesize = (sizeof (char *) * (strlen(filename)
                    + strlen(locking_prefix) + strlen(locking_suffix) + 3));
-    char *lockfilename = nmalloc(lockfilesize);
+    char *lockfilename = (char *) nmalloc(lockfilesize);
     char lockprog[12], lockuser[16];
     struct stat fileinfo;
     int lockfd, lockpid;
@@ -264,8 +264,8 @@ int do_lockfile(const char *filename)
     if (stat(lockfilename, &fileinfo) != -1) {
         ssize_t readtot = 0;
         ssize_t readamt = 0;
-        char *lockbuf = nmalloc(8192);
-        char *promptstr = nmalloc(128);
+        char *lockbuf = (char *) nmalloc(8192);
+        char *promptstr = (char *) nmalloc(128);
         int ans;
         if ((lockfd = open(lockfilename, O_RDONLY)) < 0) {
             statusbar(_("Error opening lockfile %s: %s"),
diff --git a/src/global.c b/src/global.c
index a54f6f92..566a8163 100644
--- a/src/global.c
+++ b/src/global.c
@@ -131,9 +131,9 @@ ssize_t tabsize = -1;
 char *backup_dir = NULL;
 	/* The directory where we store backup files. */
 
-char *locking_prefix = ".";
+const char *locking_prefix = ".";
         /* Prefix of how to store the vim-style lock file */
-char *locking_suffix = ".swp";
+const char *locking_suffix = ".swp";
         /* Suffix of the vim-style lock file */
 #endif
 #ifndef DISABLE_OPERATINGDIR
diff --git a/src/proto.h b/src/proto.h
index b27c9d00..94e592c4 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -85,8 +85,8 @@ extern ssize_t tabsize;
 
 #ifndef NANO_TINY
 extern char *backup_dir;
-extern char *locking_prefix;
-extern char *locking_suffix;
+extern const char *locking_prefix;
+extern const char *locking_suffix;
 #endif
 #ifndef DISABLE_OPERATINGDIR
 extern char *operating_dir;