diff --git a/smoke_test b/smoke_test
index a799e953..9a93e3ec 100755
--- a/smoke_test
+++ b/smoke_test
@@ -22,7 +22,7 @@ set -e
 
 PYTEST="${PYTEST:-pytest-3}"
 spam=$(tempfile)
-unset BCACHEFS_FUSE BCACHEFS_TEST_USE_VALGRIND D
+unset BCACHEFS_FUSE BCACHEFS_TEST_USE_VALGRIND BCACHEFS_DEBUG
 
 trap "set +x; cat ${spam}; rm -f ${spam} ; echo; echo FAILED." EXIT
 
@@ -64,7 +64,7 @@ build
 test
 
 echo -- Test: debug --
-export D=1
+export BCACHEFS_DEBUG=1
 build
 test