diff --git a/INSTALL.txt b/INSTALL.txt
index d9960fc3a0e90b414b61dae102ee68265d6b7ba9..cbd933466468848e50c5e5dc54687d9dd8cb944b 100644
--- a/INSTALL.txt
+++ b/INSTALL.txt
@@ -6,7 +6,8 @@ Prerequisites to build from source:
           Certain subsystems for embedded (core, router, mstreaming, streaming, i2ptunnel) require only Java 1.6
 	Apache Ant 1.7.0 or higher
 	The xgettext, msgfmt, and msgmerge tools installed
-	from the GNU gettext package http://www.gnu.org/software/gettext/
+	  from the GNU gettext package http://www.gnu.org/software/gettext/
+	Build environment must use a UTF-8 locale.
 
 To build and install I2P from source, you must first build
 and package up the appropriate installer by running:
diff --git a/README.txt b/README.txt
index b7a4b8e4053e2d8a1b6e1046a083e8e6bdc8b169..df6eaec0f8a36cd9325567ff52758cc3d6453050 100644
--- a/README.txt
+++ b/README.txt
@@ -5,6 +5,7 @@ Prerequisites to build from source:
 	Apache Ant 1.7.0 or higher
 	The xgettext, msgfmt, and msgmerge tools installed
 	  from the GNU gettext package http://www.gnu.org/software/gettext/
+	Build environment must use a UTF-8 locale.
 
 To build:
 	On x86 systems do: