diff --git a/libexec/bats-preprocess b/libexec/bats-preprocess
index 873085e..6cd90eb 100755
--- a/libexec/bats-preprocess
+++ b/libexec/bats-preprocess
@@ -4,6 +4,7 @@ set -e
 encode_name() {
   local name="$1"
   local result="test_"
+  local hex_code
 
   if [[ ! "$name" =~ [^[:alnum:]\ _-] ]]; then
     name="${name//_/-5f}"
@@ -21,12 +22,13 @@ encode_name() {
       elif [[ "$char" =~ [[:alnum:]] ]]; then
         result+="$char"
       else
-        result+="$(printf -- "-%02x" \'"$char")"
+        printf -v 'hex_code' -- "-%02x" \'"$char"
+        result+="$hex_code"
       fi
     done
   fi
 
-  echo "$result"
+  printf -v "$2" '%s' "$result"
 }
 
 tests=()
@@ -40,7 +42,7 @@ while IFS= read -r line; do
     quoted_name="${BASH_REMATCH[1]}"
     body="${BASH_REMATCH[2]}"
     name="$(eval echo "$quoted_name")"
-    encoded_name="$(encode_name "$name")"
+    encode_name "$name" 'encoded_name'
     tests["${#tests[@]}"]="$encoded_name"
     echo "${encoded_name}() { bats_test_begin ${quoted_name} ${index}; ${body}"
   else