diff --git a/bps/bps.project.mk b/bps/bps.project.mk
index 18fb244..3e4efed 100644
--- a/bps/bps.project.mk
+++ b/bps/bps.project.mk
@@ -95,7 +95,10 @@
 #
 #  SUBSHELLDIR [not set]
 #   A folder to change to before popping up a subshell
-
+#
+#
+#  _BSDOWL_SUBSHELL
+#   A variable set to yes if we are in a developer's subshell
 
 # Targets:
 #
@@ -393,7 +396,7 @@ PROJECTENV+=		PATH="${PROJECTLIBRARYSHELL}:${PATH}"
 SUBSHELLDIR?=		${.CURDIR}
 subshell: .PHONY
 	${INFO} "Entering developper's subshell"
-	@(cd ${.CURDIR} && cd ${SUBSHELLDIR} && ${ENVTOOL} ${PROJECTENV} ${SHELL})
+	@(cd ${.CURDIR} && cd ${SUBSHELLDIR} && ${ENVTOOL} _BSDOWL_SUBSHELL=yes ${PROJECTENV} ${SHELL})
 	${INFO} "Exiting developper's subshell"
 
 # Remove the global product file before generating dependencies