diff --git a/Makefile b/Makefile
index 872865508..4b3fb2625 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,8 @@
 # hledger project makefile
 
 # GHC-compiled executables require a locale (and not just C) or they
-# will die on encountering non-ascii data
+# will die on encountering non-ascii data.
+# Set LANG only if not already set
 export LANG?=en_US.UTF-8
 
 # command to run during "make prof" and "make heap"