diff --git a/lib/waldwaechter.sh b/lib/waldwaechter.sh
index 74cb3d8..4408078 100644
--- a/lib/waldwaechter.sh
+++ b/lib/waldwaechter.sh
@@ -248,7 +248,15 @@ function crew_doctor() {
         local lib_mtime=$(stat -f "%m" "$lib_file" 2>/dev/null || stat -c "%Y" "$lib_file" 2>/dev/null)
         local loaded_check_var="WALDWAECHTER_LOADED_${lib_mtime}"
 
-        if [[ -z "${!loaded_check_var}" ]]; then
+        # Indirect variable expansion (bash: ${!var}, zsh: ${(P)var})
+        local loaded_value=""
+        if [[ -n "$BASH_VERSION" ]]; then
+            loaded_value="${!loaded_check_var}"
+        elif [[ -n "$ZSH_VERSION" ]]; then
+            loaded_value="${(P)loaded_check_var}"
+        fi
+
+        if [[ -z "$loaded_value" ]]; then
             echo "  ⚠️  waldwaechter.sh wurde aktualisiert!"
             echo "      → Bitte neu laden: source lib/waldwaechter.sh"
             issues=$((issues + 1))