diff --git a/tests/Makefile b/tests/Makefile
index 49fe451f24..8ccd7148d6 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -2421,7 +2421,7 @@ endif
 TEST_OUTPUTDIR=output/$(TEST_TARGETSUFFIX)
 C_SUBDIR=$(TEST_OS_TARGET)/$(TEST_CPU_TARGET)
 ifneq ($(DATE),__missing_command_DATE)
-TEST_DATETIME:=$(shell $(DATE) +%Y%m%d%H%M)
+TEST_DATETIME:=$(shell $(DATE) -u +%Y%m%d%H%M)
 else
 TEST_DATETIME="No-date"
 endif
diff --git a/tests/Makefile.fpc b/tests/Makefile.fpc
index 1a1ab8a5a9..ec0ee95ba4 100644
--- a/tests/Makefile.fpc
+++ b/tests/Makefile.fpc
@@ -111,7 +111,7 @@ C_SUBDIR=$(TEST_OS_TARGET)/$(TEST_CPU_TARGET)
 
 # Date and time the testsuite was run
 ifneq ($(DATE),__missing_command_DATE)
-TEST_DATETIME:=$(shell $(DATE) +%Y%m%d%H%M)
+TEST_DATETIME:=$(shell $(DATE) -u +%Y%m%d%H%M)
 else
 # Use a spaceless string, as it will be used for file names
 TEST_DATETIME="No-date"