diff --git a/lib/utils/loader.sh b/lib/utils/loader.sh
index 4b3404b..e582d87 100644
--- a/lib/utils/loader.sh
+++ b/lib/utils/loader.sh
@@ -5,10 +5,10 @@ load_metric_with_prefix () {
   local file=$2
 
   local content=$(sed \
-          -e "s/^[[:space:]]*\(init[ ]*()[ ]*{\)/${prefix}\1/" \
-          -e "s/^[[:space:]]*\(collect[ ]*()[ ]*{\)/${prefix}\1/" \
-          -e "s/^[[:space:]]*\(terminate[ ]*()[ ]*{\)/${prefix}\1/" \
-          -e "s/^[[:space:]]*\(docs[ ]*()[ ]*{\)/${prefix}\1/" $file)
+          -e 's/^[[:space:]]*\(init[ ]*()[ ]*{\)/'"$prefix"'\1/' \
+          -e 's/^[[:space:]]*\(collect[ ]*()[ ]*{\)/'"$prefix"'\1/' \
+          -e 's/^[[:space:]]*\(terminate[ ]*()[ ]*{\)/'"$prefix"'\1/' \
+          -e 's/^[[:space:]]*\(docs[ ]*()[ ]*{\)/'"$prefix"'\1/' $file)
 
   eval "$content"
 }
@@ -17,10 +17,10 @@ load_reporter_with_prefix () {
   local prefix=$1
   local file=$2
   local content=$(sed \
-          -e "s/^[[:space:]]*\(init[ ]*()[ ]*{\)/${prefix}\1/" \
-          -e "s/^[[:space:]]*\(report[ ]*()[ ]*{\)/${prefix}\1/" \
-          -e "s/^[[:space:]]*\(terminate[ ]*()[ ]*{\)/${prefix}\1/" \
-          -e "s/^[[:space:]]*\(docs[ ]*()[ ]*{\)/${prefix}\1/" $file)
+          -e 's/^[[:space:]]*\(init[ ]*()[ ]*{\)/'"$prefix"'\1/' \
+          -e 's/^[[:space:]]*\(report[ ]*()[ ]*{\)/'"$prefix"'\1/' \
+          -e 's/^[[:space:]]*\(terminate[ ]*()[ ]*{\)/'"$prefix"'\1/' \
+          -e 's/^[[:space:]]*\(docs[ ]*()[ ]*{\)/'"$prefix"'\1/' $file)
 
   eval "$content"
 }
\ No newline at end of file