diff --git a/letsencrypt-auto-source/uname_wrapper b/letsencrypt-auto-source/uname_wrapper
index de62e5889..eda9591a4 100755
--- a/letsencrypt-auto-source/uname_wrapper
+++ b/letsencrypt-auto-source/uname_wrapper
@@ -3,7 +3,7 @@
 uname_output=$(/bin/uname_orig "$@")
 
 if [ "$UNAME_FAKE_32BITS" = true ]; then
-    uname_output="${uname_output/x86_64/i686}"
+    uname_output="${uname_output//x86_64/i686}"
 fi
 
 echo "$uname_output"