diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index f2e93f5461..2b175dc5c6 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -150,7 +150,7 @@ jobs:
     - uses: git-for-windows/setup-git-for-windows-sdk@v1
     - name: test
       shell: bash
-      run: . /etc/profile && ci/run-test-slice.sh ${{matrix.nr}} 10
+      run: . /etc/profile && ci/run-test-slice.sh ${{ matrix.nr + 1 }} 10
     - name: print test failures
       if: failure() && env.FAILED_TEST_ARTIFACTS != ''
       shell: bash
diff --git a/t/helper/test-path-utils.c b/t/helper/test-path-utils.c
index f5f33751da..874542ec34 100644
--- a/t/helper/test-path-utils.c
+++ b/t/helper/test-path-utils.c
@@ -477,14 +477,20 @@ int cmd__path_utils(int argc, const char **argv)
 
 	if (argc > 5 && !strcmp(argv[1], "slice-tests")) {
 		int res = 0;
-		long offset, stride, i;
+		long slice, slices_total, i;
 		struct string_list list = STRING_LIST_INIT_NODUP;
 		struct stat st;
 
-		offset = strtol(argv[2], NULL, 10);
-		stride = strtol(argv[3], NULL, 10);
-		if (stride < 1)
-			stride = 1;
+		slices_total = strtol(argv[3], NULL, 10);
+		if (slices_total < 1)
+			die("there must be at least one slice, got '%s'",
+			    argv[3]);
+
+		slice = strtol(argv[2], NULL, 10);
+		if (1 > slice || slice > slices_total)
+			die("slice must be in the range 1 <= slice <= %ld, got '%s'",
+			    slices_total, argv[2]);
+
 		for (i = 4; i < argc; i++)
 			if (stat(argv[i], &st))
 				res = error_errno("Cannot stat '%s'", argv[i]);
@@ -492,7 +498,7 @@ int cmd__path_utils(int argc, const char **argv)
 				string_list_append(&list, argv[i])->util =
 					(void *)(intptr_t)st.st_size;
 		QSORT(list.items, list.nr, cmp_by_st_size);
-		for (i = offset; i < list.nr; i+= stride)
+		for (i = slice - 1; i < list.nr; i+= slices_total)
 			printf("%s\n", list.items[i].string);
 
 		return !!res;