diff --git a/tools/fit_common.c b/tools/fit_common.c
index 4370de2f61..5ea43f5fec 100644
--- a/tools/fit_common.c
+++ b/tools/fit_common.c
@@ -134,7 +134,7 @@ int copyfile(const char *src, const char *dst)
 		goto out;
 	}
 
-	fd_dst = open(dst, O_WRONLY | O_CREAT, 0666);
+	fd_dst = open(dst, O_WRONLY | O_CREAT | O_TRUNC, 0666);
 	if (fd_dst < 0) {
 		printf("Can't open file %s (%s)\n", dst, strerror(errno));
 		goto out;
diff --git a/tools/fit_common.h b/tools/fit_common.h
index 872d8afa17..c600dc2ba4 100644
--- a/tools/fit_common.h
+++ b/tools/fit_common.h
@@ -44,6 +44,8 @@ int mmap_fdt(const char *cmdname, const char *fname, size_t size_inc,
  *
  * This uses read()/write() to copy file @src to file @dst
  *
+ * If @dst exists, it is overwritten and truncated to the correct size.
+ *
  * @src: Filename to read from
  * @dst: Filename to write to
  * @return 0 if OK, -1 on error