diff --git a/tests/reftests/env.test b/tests/reftests/env.test
index 1be63e186ee..0683e002409 100644
--- a/tests/reftests/env.test
+++ b/tests/reftests/env.test
@@ -15,7 +15,7 @@ Done.
 ### opam env | grep "NV_VARS" | ';' -> ':'
 NV_VARS='${BASEDIR}/OPAM/setenv/doc/nv:${BASEDIR}/OPAM/setenv/share/nv': export NV_VARS:
 ### opam exec -- opam env --revert | grep "NV_VARS" | ';' -> ':'
-NV_VARS='': export NV_VARS:
+unset NV_VARS:
 ### NV_VARS=/another/path
 ### opam env | grep "NV_VARS" | ';' -> ':'
 NV_VARS='${BASEDIR}/OPAM/setenv/doc/nv:${BASEDIR}/OPAM/setenv/share/nv:/another/path': export NV_VARS:
@@ -43,9 +43,9 @@ NV_VARS='hej!!'; export NV_VARS;
 ### opam exec -- opam env | grep "^NV_VARS|^OPAM_SWITCH_PREFIX|${OPAM}"
 OPAM_SWITCH_PREFIX='${BASEDIR}/OPAM/conffile'; export OPAM_SWITCH_PREFIX;
 NV_VARS='hej!!'; export NV_VARS;
-### opam exec -- opam env --revert | grep "^NV_VARS|^OPAM_SWITCH_PREFIX|${OPAM}"
-OPAM_SWITCH_PREFIX=''; export OPAM_SWITCH_PREFIX;
-NV_VARS=''; export NV_VARS;
+### opam exec -- opam env --revert | grep "NV_VARS|OPAM_SWITCH_PREFIX|${OPAM}"
+unset OPAM_SWITCH_PREFIX;
+unset NV_VARS;
 ### opam exec -- env | grep '^NV_VARS|^OPAM_SWITCH_PREFIX|${OPAM}'
 NV_VARS=hej!!
 OPAM=${OPAM}
@@ -67,14 +67,14 @@ set -gx NV_VARS 'hej!!';
 setenv OPAM_SWITCH_PREFIX '${BASEDIR}/OPAM/conffile';
 setenv NV_VARS 'hej!!';
 ### opam exec -- opam env --revert --shell=bash | grep -v PATH
-OPAM_SWITCH_PREFIX=''; export OPAM_SWITCH_PREFIX;
-NV_VARS=''; export NV_VARS;
+unset OPAM_SWITCH_PREFIX;
+unset NV_VARS;
 ### opam exec -- opam env --revert --shell=zsh | grep -v PATH
-OPAM_SWITCH_PREFIX=''; export OPAM_SWITCH_PREFIX;
-NV_VARS=''; export NV_VARS;
+unset OPAM_SWITCH_PREFIX;
+unset NV_VARS;
 ### opam exec -- opam env --revert --shell=fish | grep -v PATH
-set -gx OPAM_SWITCH_PREFIX '';
-set -gx NV_VARS '';
+set -ge OPAM_SWITCH_PREFIX;
+set -ge NV_VARS;
 ### opam exec -- opam env --revert --shell=csh | grep -v PATH
-setenv OPAM_SWITCH_PREFIX '';
-setenv NV_VARS '';
+unsetenv OPAM_SWITCH_PREFIX;
+unsetenv NV_VARS;