diff --git a/dracut.sh b/dracut.sh
index 58d51d71..0d67c9d4 100755
--- a/dracut.sh
+++ b/dracut.sh
@@ -882,7 +882,7 @@ unset GREP_OPTIONS
 export DRACUT_LOG_LEVEL=warning
 [[ $debug ]] && {
     export DRACUT_LOG_LEVEL=debug
-    export PS4='${BASH_SOURCE}@${LINENO}(${FUNCNAME[0]}): '
+    export PS4='${BASH_SOURCE}@${LINENO}(${FUNCNAME[0]-}): '
     set -x
 }
 
diff --git a/modules.d/99base/dracut-lib.sh b/modules.d/99base/dracut-lib.sh
index 591b97c6..43b023e1 100755
--- a/modules.d/99base/dracut-lib.sh
+++ b/modules.d/99base/dracut-lib.sh
@@ -392,7 +392,7 @@ setdebug() {
             if getargbool 0 rd.debug -d -y rdinitdebug -d -y rdnetdebug; then
                 RD_DEBUG=yes
                 [ -n "$BASH" ] \
-                    && export PS4='${BASH_SOURCE}@${LINENO}(${FUNCNAME[0]}): '
+                    && export PS4='${BASH_SOURCE}@${LINENO}(${FUNCNAME[0]-}): '
             fi
         fi
         export RD_DEBUG