diff --git a/debian/tests/installcheck b/debian/tests/installcheck
index 5ae27c7..881e826 100755
--- a/debian/tests/installcheck
+++ b/debian/tests/installcheck
@@ -2,8 +2,10 @@
 
 if [ -f /etc/locale.gen ]; then
 	# Debian
-	grep -Fq "en_US.UTF-8 UTF-8" || echo "en_US.UTF-8 UTF-8" >> /etc/locale.gen
-	locale-gen
+	if ! grep -Fwq "en_US.UTF-8 UTF-8" /etc/locale.gen; then
+		echo "en_US.UTF-8 UTF-8" >> /etc/locale.gen
+		locale-gen
+	fi
 else
 	# Ubuntu
 	locale-gen en_US.UTF-8