diff --git a/update_psa b/update_psa
index 4d8c014..d94e477 100755
--- a/update_psa
+++ b/update_psa
@@ -25,6 +25,7 @@ if [ -z $IFS ]; then
 fi
 
 MAINTENANCE="NO"
+WORKING_DIRECTORY=${PWD}
 
 # parse commandline parameters
 while test $# -gt 0; do
@@ -66,42 +67,46 @@ while test $# -gt 0; do
     esac
     shift
 done
+    
+source ./update_psa_impl
 
-if cd "$WORKING_DIRECTORY"; then
-    source ./update_psa_impl
-
-    if read_config
-    then
-        check_default_route
-        check_route_to_repository "185.191.219.134" # git.mimbach.de
-        check_for_running_apism
-        if clone_customer_repository ${CUSTOMER_REPOSITORY_PATH}
-	    then 
-            check_sanity_of_repository
-
-            if [ "$MAINTENANCE" = "NO" ]; then
-                log_info "update_psa:${LINENO}: MAINTENANCE OFF. Checking for updates..."
-                # someone must have activated the WAIT-button in ISMAS. 
-                # Request the status of this button in updates_available().
-                if ! updates_available; then 
-                    update_psa_false_alarm "update requested, but no WAIT state detected !!!"
-                    log_fatal "update_psa:${LINENO}: update requested, but no WAIT state detected !!!"
-                fi
-            else
-                # simulate an activated WAIT-button
-                set_updates_available
-                while :
-                do
-                    sleep 5
-                    updates_available && break
-                done 
-            fi
-            # updates available
-            update_psa
-        fi
-    fi
-    exit 0
+if [ -z "$WORKING_DIRECTORY" ]; then
+    log_fatal "update_psa:${LINENO}: empty WORKING_DIRECTORY"
 fi
 
-exit -1
+if ! cd "$WORKING_DIRECTORY"; then
+    log_fatal "update_psa:${LINENO}: cannot cd to $WORKING_DIRECTORY"
+fi
+        
+log_info "update_psa:${LINENO}: cd to $WORKING_DIRECTORY"
+
+if read_config; then
+    check_default_route
+    check_route_to_repository "185.191.219.134" # git.mimbach.de
+    check_for_running_apism
+    if clone_customer_repository ${CUSTOMER_REPOSITORY_PATH}; then 
+        check_sanity_of_repository
+
+        if [ "$MAINTENANCE" = "NO" ]; then
+            log_info "update_psa:${LINENO}: MAINTENANCE OFF. Checking for updates..."
+            # someone must have activated the WAIT-button in ISMAS. 
+            # Request the status of this button in updates_available().
+            if ! updates_available; then 
+                update_psa_false_alarm "update requested, but no WAIT state detected !!!"
+                log_fatal "update_psa:${LINENO}: update requested, but no WAIT state detected !!!"
+            fi
+        else
+            # simulate an activated WAIT-button
+            set_updates_available
+            while :
+            do
+                sleep 5
+                updates_available && break
+            done 
+        fi
+        # updates available
+        update_psa
+    fi
+fi
+exit 0
 ###############################################################################