diff --git a/tests/Makefile b/tests/Makefile
index 59a413fc71..f2c858a073 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -2637,7 +2637,7 @@ endif
 	-$(MKDIRTREE) $(TEST_OUTPUTDIR)/test/units/system
 testprep: testprep-stamp.$(TEST_FULL_TARGET)
 testprep-stamp.$(TEST_FULL_TARGET): utils tstunits copyfiles
-	$(ECHOREDIR) $(DATE) > testprep-stamp.$(TEST_FULL_TARGET)
+	$(ECHOREDIR) $(TEST_DATETIME) > testprep-stamp.$(TEST_FULL_TARGET)
 ifneq ($(TEST_FPC),ppc386$(EXEEXT))
 ifeq ($(findstring -c$(TEST_FPC),$(DOTESTOPT)),)
 override DOTESTOPT+=-c$(TEST_FPC)
diff --git a/tests/Makefile.fpc b/tests/Makefile.fpc
index c3cbfac18b..e5d13d57ac 100644
--- a/tests/Makefile.fpc
+++ b/tests/Makefile.fpc
@@ -296,7 +296,7 @@ endif
 
 testprep: testprep-stamp.$(TEST_FULL_TARGET)
 testprep-stamp.$(TEST_FULL_TARGET): utils tstunits copyfiles
-        $(ECHOREDIR) $(DATE) > testprep-stamp.$(TEST_FULL_TARGET)
+        $(ECHOREDIR) $(TEST_DATETIME) > testprep-stamp.$(TEST_FULL_TARGET)
 
 ################################
 # Dotest options