diff --git a/scripts/monitor-interrupt-rate b/scripts/monitor-interrupt-rate
index 7e81ed9a5..ee2e70be5 100755
--- a/scripts/monitor-interrupt-rate
+++ b/scripts/monitor-interrupt-rate
@@ -2,6 +2,12 @@
 
 interval="${1:-5}"
 
+if ! [[ "$interval" =~ ^0*[1-9][0-9]*$ ]]; then
+  echo "Error: interval must be a positive integer." >&2
+  exit 1
+fi
+interval="${interval#"${interval%%[!0]*}"}"
+
 echo "Interrupts per second:"
 while true
 do
diff --git a/scripts/monitor-memory-usage b/scripts/monitor-memory-usage
index eabb74dba..09b5d33e2 100755
--- a/scripts/monitor-memory-usage
+++ b/scripts/monitor-memory-usage
@@ -50,10 +50,11 @@ do
   esac
 done
 
-if [ "$#" != 0 ] || [ "${interval}" -le 0 ]; then
+if [ "$#" != 0 ] || ! [[ "${interval}" =~ ^0*[1-9][0-9]*$ ]]; then
   usage
   exit 1
 fi
+interval="${interval#"${interval%%[!0]*}"}"
 
 
 ####################