diff --git a/modules/security/malware-scanner.sh b/modules/security/malware-scanner.sh
index 90771c8..fde9f33 100755
--- a/modules/security/malware-scanner.sh
+++ b/modules/security/malware-scanner.sh
@@ -730,10 +730,10 @@ show_spinner() {
 
     while kill -0 "$pid" 2>/dev/null; do
         i=$(( (i+1) % 10 ))
-        printf "\r  ⏳ $message ${spin:$i:1} "
+        printf "\r  ⏳ %s %s " "$message" "${spin:$i:1}"
         sleep 0.2
     done
-    printf "\r  ✓ $message - Complete\n"
+    printf "\r  ✓ %s - Complete\n" "$message"
 }
 
 # Format elapsed time
@@ -1270,7 +1270,8 @@ for scanner in "${AVAILABLE_SCANNERS[@]}"; do
 
             # Wait for all maldet scans to complete and collect exit codes
             for pid in "${MALDET_PIDS[@]}"; do
-                if [ -n "$pid" ] && kill -0 "$pid" 2>/dev/null; then
+                # Validate PID is numeric and non-zero before checking process
+                if [ -n "$pid" ] && [ "$pid" -gt 0 ] && kill -0 "$pid" 2>/dev/null; then
                     wait "$pid"
                     exit_code=$?
                     if [ "$exit_code" -ne 0 ]; then