diff --git a/core/cfs/cfs-coffee.c b/core/cfs/cfs-coffee.c
index 37b1a707e..374b3419f 100644
--- a/core/cfs/cfs-coffee.c
+++ b/core/cfs/cfs-coffee.c
@@ -196,7 +196,7 @@ struct file_header {
 /* This is needed because of a buggy compiler. */
 struct log_param {
   cfs_offset_t offset;
-  const char *buf;
+  char *buf;
   uint16_t size;
 };
 
@@ -1198,7 +1198,7 @@ cfs_write(int fd, const void *buf, unsigned size)
     need_dummy_write = 0;
     for(bytes_left = size; bytes_left > 0;) {
       lp.offset = fdp->offset;
-      lp.buf = buf;
+      lp.buf = (void *)buf;
       lp.size = bytes_left;
       i = write_log_page(file, &lp);
       if(i < 0) {