diff --git a/.github/workflows/unit_tests.sh b/.github/workflows/unit_tests.sh
index dc5bf5dd4fc..c1a5ede3833 100755
--- a/.github/workflows/unit_tests.sh
+++ b/.github/workflows/unit_tests.sh
@@ -73,7 +73,8 @@ for phase in "${PHASES[@]}"; do
             MESON_ARGS+=(--fatal-meson-warnings)
             run_meson -Dnobody-group=nogroup --werror -Dtests=unsafe -Dslow-tests=true -Dfuzz-tests=true "${MESON_ARGS[@]}" build
             ninja -C build -v
-            meson test -C build --print-errorlogs
+            # Ensure setting a timezone (like the reproducible build tests do) does not break time/date unit tests
+            TZ=GMT+12 meson test -C build --print-errorlogs
             ;;
         RUN_ASAN_UBSAN|RUN_GCC_ASAN_UBSAN|RUN_CLANG_ASAN_UBSAN|RUN_CLANG_ASAN_UBSAN_NO_DEPS)
             MESON_ARGS=(--optimization=1)
diff --git a/src/test/test-calendarspec.c b/src/test/test-calendarspec.c
index db64142f01c..18a0f8f8bfd 100644
--- a/src/test/test-calendarspec.c
+++ b/src/test/test-calendarspec.c
@@ -254,4 +254,11 @@ TEST(calendar_spec_from_string) {
         assert_se(calendar_spec_from_string("*:4,30:*\n", &c) == -EINVAL);
 }
 
-DEFINE_TEST_MAIN(LOG_INFO);
+static int intro(void) {
+        /* Tests have hard-coded results that do not expect a specific timezone to be set by the caller */
+        assert_se(unsetenv("TZ") >= 0);
+
+        return EXIT_SUCCESS;
+}
+
+DEFINE_TEST_MAIN_WITH_INTRO(LOG_INFO, intro);
diff --git a/src/test/test-date.c b/src/test/test-date.c
index a7058a33d42..162ac342f50 100644
--- a/src/test/test-date.c
+++ b/src/test/test-date.c
@@ -62,6 +62,9 @@ static void test_one_noutc(const char *p) {
 }
 
 int main(int argc, char *argv[]) {
+        /* Tests have hard-coded results that do not expect a specific timezone to be set by the caller */
+        assert_se(unsetenv("TZ") >= 0);
+
         test_setup_logging(LOG_DEBUG);
 
         test_one("17:41");
diff --git a/src/test/test-time-util.c b/src/test/test-time-util.c
index d29afa38dd2..9ce014dc9e3 100644
--- a/src/test/test-time-util.c
+++ b/src/test/test-time-util.c
@@ -1171,6 +1171,9 @@ TEST(timezone_offset_change) {
 }
 
 static int intro(void) {
+        /* Tests have hard-coded results that do not expect a specific timezone to be set by the caller */
+        assert_se(unsetenv("TZ") >= 0);
+
         log_info("realtime=" USEC_FMT "\n"
                  "monotonic=" USEC_FMT "\n"
                  "boottime=" USEC_FMT "\n",