diff --git a/.gitignore b/.gitignore
index b9e09a1..fdbe54e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,6 +4,8 @@
 *.md~
 .gitignore~
 .scala~
+*.sh~
+*.py~
 *.scala~
 
 # sbt specific
diff --git a/doc/BUILD.md b/doc/BUILD.md
index 2501a51..525054c 100644
--- a/doc/BUILD.md
+++ b/doc/BUILD.md
@@ -1,6 +1,8 @@
 Compiling
 =========
 
+To build `units` 0.1.x, you need sbt 0.12.x.
+
 To compile the code, run `sbt` and execute:
 
 	compile