diff --git a/includes/miniffs.h b/includes/miniffs.h
index 57b67bf..1c1adba 100644
--- a/includes/miniffs.h
+++ b/includes/miniffs.h
@@ -85,7 +85,7 @@ enum
  */
 
 /* miniffs_openfs is backend specific and will be found in the backend header file */
-file_t *miniffs_open(miniffs_t *fs, char *filename);                         /***< Open a file */
+file_t *miniffs_open(miniffs_t *fs, const char *filename);                         /***< Open a file */
 int miniffs_close(file_t *file);                                             /***< Close a file */
 void *miniffs_map(file_t *file);                                             /***< Map a file to memory */
 int miniffs_read_blocks(void *ptr, size_t size, size_t nmemb, file_t *file); /***< Read blocks of bytes from a file */
@@ -123,7 +123,7 @@ int miniffs_closefs(miniffs_t *fs);
  * Function that are private to the library
  */
 bool miniffs_isvalidfs(miniffs_t *fs);
-fileentry_t *miniffs_findfile(miniffs_t *fs, char *filename);
+fileentry_t *miniffs_findfile(miniffs_t *fs, const char *filename);
 void miniffs_seterror(miniffs_error_t err);
 void *miniffs_getfileaddr(miniffs_t *fs, fileentry_t *fent);
 #endif /* __miniffs_internal */
diff --git a/miniffs.c b/miniffs.c
index 15660d7..cd4a261 100644
--- a/miniffs.c
+++ b/miniffs.c
@@ -16,7 +16,7 @@ static miniffs_error_t last_error = MINIFFS_NOERROR;
 
 /* Public API */
 
-file_t *miniffs_open(miniffs_t *fs, char *filename)
+file_t *miniffs_open(miniffs_t *fs, const char *filename)
 {
     file_t *ret = (file_t *)calloc(1, sizeof(file_t));
     if (ret == NULL)
@@ -150,7 +150,7 @@ static void make_fullname(char *name, char *ext, char *out)
     memcpy(out + nameLen + 1, ext, extLen);
 }
 
-fileentry_t *miniffs_findfile(miniffs_t *fs, char *filename)
+fileentry_t *miniffs_findfile(miniffs_t *fs, const char *filename)
 {
     int i;
     char entryFullName[MINIFFS_FULLNAME_LENGTH];