diff --git a/hooks/infracost_breakdown.sh b/hooks/infracost_breakdown.sh
index 5515791..121f49b 100755
--- a/hooks/infracost_breakdown.sh
+++ b/hooks/infracost_breakdown.sh
@@ -70,19 +70,24 @@ function infracost_breakdown_ {
     # -h .totalHourlyCost > 0.1
     # --hook-config=.currency == "USD"
     first_char=${check:0:1}
-    last_char=${check: -1}
+    last_char=${check:$((${#check} - 1)):1}
     if [ "$first_char" == "$last_char" ] && {
       [ "$first_char" == '"' ] || [ "$first_char" == "'" ]
     }; then
-      check="${check:1:-1}"
+      check="${check:1:$((${#check} - 2))}"
     fi
 
-    mapfile -t operations < <(echo "$check" | grep -oE '[!<>=]{1,2}')
+    # Replace mapfile with while read loop for bash 3.2 compatibility
+    operations=()
+    while IFS= read -r line; do
+      operations+=("$line")
+    done < <(echo "$check" | grep -oE '[!<>=]{1,2}')
+
     # Get the very last operator, that is used in comparison inside `jq` query.
     # From the example below we need to pick the `>` which is in between `add` and `1000`,
     # but not the `!=`, which goes earlier in the `jq` expression
     # [.projects[].diff.totalMonthlyCost | select (.!=null) | tonumber] | add > 1000
-    operation=${operations[-1]}
+    operation=${operations[$((${#operations[@]} - 1))]}
 
     IFS="$operation" read -r -a jq_check <<< "$check"
     real_value="$(jq "${jq_check[0]}" <<< "$RESULTS")"