diff --git a/rsync.h b/rsync.h
index 3e040d4f..a31b7e2c 100644
--- a/rsync.h
+++ b/rsync.h
@@ -32,7 +32,7 @@
 #define BACKUP_SUFFIX "~"
 
 /* a non-zero CHAR_OFFSET makes the rolling sum stronger, but is
-   imcompatible with older versions :-( */
+   incompatible with older versions :-( */
 #define CHAR_OFFSET 0