Index: /trunk/Config.kmk
===================================================================
--- /trunk/Config.kmk	(revision 75189)
+++ /trunk/Config.kmk	(revision 75190)
@@ -3625,5 +3625,5 @@
 	--force \
 	--file-list - \
-	$(if-expr VBOX_TSA_URL,--timestamp="$(VBOX_TSA_URL)") \
+	$(if-expr defined(VBOX_TSA_URL),--timestamp="$(VBOX_TSA_URL)") \
        $(3) \
 	$(VBOX_CERTIFICATE_SUBJECT_NAME_ARGS) \
@@ -3637,5 +3637,5 @@
 	--force \
 	--file-list - \
-	$(if-expr VBOX_TSA_URL,--timestamp="$(VBOX_TSA_URL)") \
+	$(if-expr defined(VBOX_TSA_URL),--timestamp="$(VBOX_TSA_URL)") \
 	$(VBOX_CERTIFICATE_SUBJECT_NAME_ARGS) \
 	$(1) \
@@ -3654,5 +3654,5 @@
 	--force \
 	--file-list - \
-	$(if-expr VBOX_TSA_URL,--timestamp="$(VBOX_TSA_URL)") \
+	$(if-expr defined(VBOX_TSA_URL),--timestamp="$(VBOX_TSA_URL)") \
 	$(VBOX_CERTIFICATE_SUBJECT_NAME_ARGS) \
 	$(1) \