diff --git a/src/fileio.c b/src/fileio.c
index 9e27ef2..fb80f49 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -148,6 +148,7 @@ bool load_game (int num)
     char *buf, *filename;
     FILE *file;
     int saved_errno, lineno;
+    char *prev_locale;
 
     int crypt_key;
     int n, i, j, x, y;
@@ -203,6 +204,9 @@ bool load_game (int num)
 	return false;
     }
 
+    // Change the formatting of numbers to the POSIX locale
+    prev_locale = setlocale(LC_NUMERIC, "C");
+
     // Read the game file header
     if (fgets(buf, BUFSIZE, file) == NULL) {
 	err_exit("%s: missing header in game file", filename);
@@ -287,6 +291,9 @@ bool load_game (int num)
 	errno_exit("%s", filename);
     }
 
+    // Change the formatting of numbers back to the user-supplied locale
+    setlocale(LC_NUMERIC, prev_locale);
+
     free(buf);
     free(filename);
     return true;
@@ -308,6 +315,7 @@ bool save_game (int num)
     char *buf, *filename;
     FILE *file;
     int saved_errno;
+    char *prev_locale;
     struct stat statbuf;
     int crypt_key;
     int i, j, x, y;
@@ -379,6 +387,9 @@ bool save_game (int num)
 	return false;
     }
 
+    // Change the formatting of numbers to the POSIX locale
+    prev_locale = setlocale(LC_NUMERIC, "C");
+
     // Write out the game file header and encryption key
     fprintf(file, "%s\n" "%s\n", GAME_FILE_HEADER, GAME_FILE_API_VERSION);
     fprintf(file, "%d\n", crypt_key);
@@ -435,6 +446,9 @@ bool save_game (int num)
 	errno_exit("%s", filename);
     }
 
+    // Change the formatting of numbers back to the user-supplied locale
+    setlocale(LC_NUMERIC, prev_locale);
+
     free(buf);
     free(filename);
     return true;