diff --git a/lang/qt/tests/Makefile.am b/lang/qt/tests/Makefile.am
index 65fd0196..0815984c 100644
--- a/lang/qt/tests/Makefile.am
+++ b/lang/qt/tests/Makefile.am
@@ -1,118 +1,118 @@
 # Makefile.am - Makefile for GPGME Qt tests.
 # Copyright (C) 2016 Bundesamt für Sicherheit in der Informationstechnik
 # Software engineering by Intevation GmbH
 #
 # This file is part of GPGME.
 #
 # GPGME is free software; you can redistribute it and/or modify it
 # under the terms of the GNU Lesser General Public License as
 # published by the Free Software Foundation; either version 2.1 of the
 # License, or (at your option) any later version.
 #
 # GPGME is distributed in the hope that it will be useful, but WITHOUT
 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 # or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General
 # Public License for more details.
 #
 # You should have received a copy of the GNU Lesser General Public
 # License along with this program; if not, see <https://www.gnu.org/licenses/>.
 
 ## Process this file with automake to produce Makefile.in
 
 GPG = gpg
 
 GNUPGHOME=$(abs_builddir)
-TESTS_ENVIRONMENT = GNUPGHOME=$(GNUPGHOME)
+TESTS_ENVIRONMENT = GNUPGHOME=$(GNUPGHOME) TZ=UTC
 
 EXTRA_DIST = initial.test final.test
 
 the_tests = \
 	t-addexistingsubkey \
 	t-keylist t-keylocate t-ownertrust t-tofuinfo \
 	t-encrypt t-verify t-various t-config t-remarks t-trustsignatures \
 	t-changeexpiryjob t-wkdlookup t-import t-revokekey
 
 TESTS = initial.test $(the_tests) final.test
 
 moc_files = \
 	t-addexistingsubkey.moc \
 	t-keylist.moc t-keylocate.moc t-ownertrust.moc t-tofuinfo.moc \
 	t-encrypt.moc t-support.hmoc t-wkspublish.moc t-verify.moc \
 	t-various.moc t-config.moc t-remarks.moc t-trustsignatures.moc \
 	t-changeexpiryjob.moc t-wkdlookup.moc t-import.moc t-revokekey.moc
 
 AM_LDFLAGS = -no-install
 
 LDADD = ../../cpp/src/libgpgmepp.la ../src/libqgpgme.la \
         ../../../src/libgpgme.la @GPGME_QT_LIBS@ @GPG_ERROR_LIBS@ \
         @GPGME_QTTEST_LIBS@ @LDADD_FOR_TESTS_KLUDGE@ -lstdc++
 
 AM_CPPFLAGS = -I$(top_srcdir)/lang/cpp/src -I$(top_builddir)/src \
               @GPG_ERROR_CFLAGS@ @GPGME_QT_CFLAGS@ @GPG_ERROR_CFLAGS@ \
               @LIBASSUAN_CFLAGS@ @GPGME_QTTEST_CFLAGS@ -DBUILDING_QGPGME \
               -I$(top_srcdir)/lang/qt/src \
               -DTOP_SRCDIR="$(top_srcdir)"
 
 support_src = t-support.h t-support.cpp
 
 t_addexistingsubkey_SOURCES = t-addexistingsubkey.cpp $(support_src)
 t_keylist_SOURCES = t-keylist.cpp $(support_src)
 t_keylocate_SOURCES = t-keylocate.cpp $(support_src)
 t_ownertrust_SOURCES = t-ownertrust.cpp $(support_src)
 t_tofuinfo_SOURCES = t-tofuinfo.cpp $(support_src)
 t_encrypt_SOURCES = t-encrypt.cpp $(support_src)
 t_wkspublish_SOURCES = t-wkspublish.cpp $(support_src)
 t_verify_SOURCES = t-verify.cpp $(support_src)
 t_various_SOURCES = t-various.cpp $(support_src)
 t_config_SOURCES = t-config.cpp $(support_src)
 t_remarks_SOURCES = t-remarks.cpp $(support_src)
 t_trustsignatures_SOURCES = t-trustsignatures.cpp $(support_src)
 t_changeexpiryjob_SOURCES = t-changeexpiryjob.cpp $(support_src)
 t_wkdlookup_SOURCES = t-wkdlookup.cpp $(support_src)
 t_import_SOURCES = t-import.cpp $(support_src)
 t_revokekey_SOURCES = t-revokekey.cpp $(support_src)
 run_exportjob_SOURCES = run-exportjob.cpp
 run_importjob_SOURCES = run-importjob.cpp
 run_keyformailboxjob_SOURCES = run-keyformailboxjob.cpp
 run_receivekeysjob_SOURCES = run-receivekeysjob.cpp
 run_refreshkeysjob_SOURCES = run-refreshkeysjob.cpp
 
 nodist_t_keylist_SOURCES = $(moc_files)
 
 BUILT_SOURCES = $(moc_files) pubring-stamp
 
 noinst_PROGRAMS = \
 	t-addexistingsubkey \
 	t-keylist t-keylocate t-ownertrust t-tofuinfo t-encrypt \
 	run-keyformailboxjob t-wkspublish t-verify t-various t-config t-remarks \
 	t-trustsignatures t-changeexpiryjob t-wkdlookup t-import t-revokekey \
 	run-importjob run-exportjob run-receivekeysjob run-refreshkeysjob
 
 CLEANFILES = secring.gpg pubring.gpg pubring.kbx trustdb.gpg dirmngr.conf \
 	gpg-agent.conf pubring.kbx~ S.gpg-agent gpg.conf pubring.gpg~ \
 	random_seed S.gpg-agent .gpg-v21-migrated pubring-stamp $(moc_files) \
 	gpg.conf tofu.db reader_0.status reader_1.status
 
 clean-local:
 	-$(TESTS_ENVIRONMENT) $(top_srcdir)/tests/start-stop-agent --stop
 	-rm -fR  private-keys-v1.d crls.d
 
 pubring-stamp: $(top_srcdir)/tests/gpg/pubdemo.asc \
 	             $(top_srcdir)/tests/gpg/secdemo.asc
 	-$(TESTS_ENVIRONMENT) gpgconf --kill all
 	echo "ignore-invalid-option allow-loopback-pinentry" > $(abs_builddir)/gpg-agent.conf
 	echo "allow-loopback-pinentry" >> gpg-agent.conf
 	echo "ignore-invalid-option pinentry-mode" > gpg.conf
 	echo "pinentry-mode loopback" >> gpg.conf
 	$(TESTS_ENVIRONMENT) $(GPG) --no-permission-warning \
            --import $(top_srcdir)/tests/gpg/pubdemo.asc
 	$(TESTS_ENVIRONMENT) $(GPG) --no-permission-warning \
 		   --passphrase "abc" \
            --import $(top_srcdir)/tests/gpg/secdemo.asc
 	touch pubring-stamp
 
 .cpp.moc:
 	$(MOC) `test -f '$<' || echo '$(srcdir)/'`$< -o $@
 
 .h.hmoc:
 	$(MOC) `test -f '$<' || echo '$(srcdir)/'`$< -o $@
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 99b6fb46..3ff86b6e 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -1,63 +1,63 @@
 # Makefile.am - Makefile for GPGME tests.
 # Copyright (C) 2000 Werner Koch (dd9jn)
 # Copyright (C) 2001, 2004 g10 Code GmbH
 #
 # This file is part of GPGME.
 #
 # GPGME is free software; you can redistribute it and/or modify it
 # under the terms of the GNU Lesser General Public License as
 # published by the Free Software Foundation; either version 2.1 of the
 # License, or (at your option) any later version.
 #
 # GPGME is distributed in the hope that it will be useful, but WITHOUT
 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 # or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General
 # Public License for more details.
 #
 # You should have received a copy of the GNU Lesser General Public
 # License along with this program; if not, see <https://gnu.org/licenses/>.
 # SPDX-License-Identifier: LGPL-2.1-or-later
 
 ## Process this file with automake to produce Makefile.in
 
 GNUPGHOME=$(abs_builddir)
-TESTS_ENVIRONMENT = GNUPGHOME=$(GNUPGHOME)
+TESTS_ENVIRONMENT = GNUPGHOME=$(GNUPGHOME) TZ=UTC
 
 TESTS = t-version t-data t-engine-info
 
 EXTRA_DIST = start-stop-agent t-data-1.txt t-data-2.txt ChangeLog-2011
 
 AM_CPPFLAGS = -I$(top_builddir)/src @GPG_ERROR_CFLAGS@
 
 if HAVE_W32_SYSTEM
 AM_LDFLAGS = -no-fast-install
 else
 AM_LDFLAGS = -no-install
 endif
 
 LDADD = ../src/libgpgme.la @GPG_ERROR_LIBS@ @LDADD_FOR_TESTS_KLUDGE@
 
 noinst_HEADERS = run-support.h
 
 noinst_PROGRAMS = $(TESTS) run-keylist run-export run-import run-sign \
 		  run-verify run-encrypt run-identify run-decrypt run-genkey \
 		  run-keysign run-tofu run-swdb run-threaded \
 		  run-receive-keys
 
 run_threaded_CPPFLAGS = -I$(top_builddir)/src @GPG_ERROR_MT_CFLAGS@
 run_threaded_LDADD = ../src/libgpgme.la \
 		     @GPG_ERROR_MT_LIBS@ @LDADD_FOR_TESTS_KLUDGE@
 
 if RUN_GPG_TESTS
 gpgtests = gpg json
 else
 gpgtests =
 endif
 
 if RUN_GPGSM_TESTS
 gpgsmtests = gpgsm opassuan
 else
 gpgsmtests =
 endif
 
 SUBDIRS = ${gpgtests} ${gpgsmtests}