diff --git a/help.c b/help.c
index 19328ea..2ff3b5a 100644
--- a/help.c
+++ b/help.c
@@ -419,6 +419,12 @@
 	 * with external projects that rely on the output of "git version".
 	 */
 	printf("git version %s\n", git_version_string);
+	while (*++argv) {
+		if (!strcmp(*argv, "--build-options")) {
+			printf("sizeof-long: %d\n", (int)sizeof(long));
+			/* NEEDSWORK: also save and output GIT-BUILD_OPTIONS? */
+		}
+	}
 	return 0;
 }
 
diff --git a/t/t0006-date.sh b/t/t0006-date.sh
index 04ce535..4c8cf58 100755
--- a/t/t0006-date.sh
+++ b/t/t0006-date.sh
@@ -31,7 +31,7 @@
 	format=$1
 	time=$2
 	expect=$3
-	test_expect_${4:-success} "show date ($format:$time)" '
+	test_expect_success $4 "show date ($format:$time)" '
 		echo "$time -> $expect" >expect &&
 		test-date show:$format "$time" >actual &&
 		test_cmp expect actual
@@ -50,8 +50,8 @@
 
 # arbitrary time absurdly far in the future
 FUTURE="5758122296 -0400"
-check_show iso       "$FUTURE" "2152-06-19 18:24:56 -0400"
-check_show iso-local "$FUTURE" "2152-06-19 22:24:56 +0000"
+check_show iso       "$FUTURE" "2152-06-19 18:24:56 -0400" LONG_IS_64BIT
+check_show iso-local "$FUTURE" "2152-06-19 22:24:56 +0000" LONG_IS_64BIT
 
 check_parse() {
 	echo "$1 -> $2" >expect
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 0055ebb..11201e9 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -1111,3 +1111,12 @@
 }
 
 test_lazy_prereq CMDLINE_LIMIT 'run_with_limited_cmdline true'
+
+build_option () {
+	git version --build-options |
+	sed -ne "s/^$1: //p"
+}
+
+test_lazy_prereq LONG_IS_64BIT '
+	test 8 -le "$(build_option sizeof-long)"
+'