diff --git a/makehdimage b/makehdimage
index 45a2f656d7..c80dfa22a3 100755
--- a/makehdimage
+++ b/makehdimage
@@ -97,7 +97,10 @@ resattr=$sourceDir/objects/${arch}.R1/tools/resattr/resattr
 fsShellCommand=$sourceDir/objects/${arch}.R1/tests/add-ons/kernel/file_systems/fs_shell/fs_shell_command
 bfsShell=$sourceDir/objects/${arch}.R1/tests/add-ons/kernel/file_systems/bfs/bfs_shell/bfs_shell
 
-export RUN_WITHOUT_APP_SERVER=1
+if [ x$RUN_WITHOUT_APP_SERVER != x ]; then
+	# define only, if not already set
+	export RUN_WITHOUT_APP_SERVER=1
+fi
 export TARGET_PLATFORM=haiku
 
 BEOS_BIN="touch sync ln listarea listattr listsem listport \
diff --git a/src/kits/Jamfile b/src/kits/Jamfile
index e8aeb4842c..26912ad2ae 100644
--- a/src/kits/Jamfile
+++ b/src/kits/Jamfile
@@ -14,7 +14,8 @@ if $(RUN_WITHOUT_REGISTRAR) {
 
 # If defined allows to run applications without the app server
 # -- needed until the app server runs on our kernel.
-if $(RUN_WITHOUT_APP_SERVER) {
+RUN_WITHOUT_APP_SERVER ?= 0 ;
+if $(RUN_WITHOUT_APP_SERVER) != 0 {
 	local defines = [ FDefines RUN_WITHOUT_APP_SERVER ] ;
 	SubDirCcFlags $(defines) ;
 	SubDirC++Flags $(defines) ;