diff --git a/osbase/logtree/logtree_access_test.go b/osbase/logtree/logtree_access_test.go
new file mode 100644
index 0000000..8379fd3
--- /dev/null
+++ b/osbase/logtree/logtree_access_test.go
@@ -0,0 +1,166 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package logtree
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+)
+
+func TestJournalStartPosition(t *testing.T) {
+	lt := New()
+
+	for i := 0; i < 100; i += 1 {
+		e := &entry{
+			origin:  "main",
+			leveled: testPayload(fmt.Sprintf("test %d", i)),
+		}
+		lt.journal.append(e)
+	}
+
+	type tCase struct {
+		name string
+
+		count     int
+		direction ReadDirection
+		pos       int
+
+		expectedCount int
+		expectedFirst string
+		expectedLast  string
+	}
+
+	for _, tc := range []tCase{
+		{
+			name:      "fetch all before id 0",
+			count:     BacklogAllAvailable,
+			direction: ReadDirectionBefore,
+			pos:       0,
+
+			expectedCount: 0,
+			expectedFirst: "UNREACHABLE",
+			expectedLast:  "UNREACHABLE",
+		},
+		{
+			name:      "fetch all after id 0",
+			count:     BacklogAllAvailable,
+			direction: ReadDirectionAfter,
+			pos:       0,
+
+			expectedCount: 100,
+			expectedFirst: "test 0",
+			expectedLast:  "test 99",
+		},
+
+		{
+			name:      "fetch all before id 10",
+			count:     BacklogAllAvailable,
+			direction: ReadDirectionBefore,
+			pos:       10,
+
+			expectedCount: 10,
+			expectedFirst: "test 0",
+			expectedLast:  "test 9",
+		},
+		{
+			name:      "fetch all after id 10",
+			count:     BacklogAllAvailable,
+			direction: ReadDirectionAfter,
+			pos:       10,
+
+			expectedCount: 90,
+			expectedFirst: "test 10",
+			expectedLast:  "test 99",
+		},
+
+		{
+			name:      "fetch 10 before id 0",
+			count:     10,
+			direction: ReadDirectionBefore,
+			pos:       0,
+
+			expectedCount: 0,
+			expectedFirst: "UNREACHABLE",
+			expectedLast:  "UNREACHABLE",
+		},
+		{
+			name:      "fetch 10 after id 0",
+			count:     10,
+			direction: ReadDirectionAfter,
+			pos:       0,
+
+			expectedCount: 10,
+			expectedFirst: "test 0",
+			expectedLast:  "test 9",
+		},
+
+		{
+			name:      "fetch 10 before id 3",
+			count:     10,
+			direction: ReadDirectionBefore,
+			pos:       3,
+
+			expectedCount: 3,
+			expectedFirst: "test 0",
+			expectedLast:  "test 2",
+		},
+		{
+			name:      "fetch 10 after id 3",
+			count:     10,
+			direction: ReadDirectionAfter,
+			pos:       3,
+
+			expectedCount: 10,
+			expectedFirst: "test 3",
+			expectedLast:  "test 12",
+		},
+		{
+			name:      "fetch 43 before id 47",
+			count:     43,
+			direction: ReadDirectionBefore,
+			pos:       47,
+
+			expectedCount: 43,
+			expectedFirst: "test 4",
+			expectedLast:  "test 46",
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			lr, _ := lt.Read("main",
+				WithBacklog(tc.count),
+				WithStartPosition(tc.pos, tc.direction),
+			)
+			if l := len(lr.Backlog); l != tc.expectedCount {
+				t.Fatalf("expected %d entries, got %d", tc.expectedCount, l)
+			}
+			if len(lr.Backlog) == 0 {
+				// If there is nothing to test against, skip to next test.
+				return
+			}
+			if first := strings.Join(lr.Backlog[0].Leveled.messages, "\n"); first != tc.expectedFirst {
+				t.Errorf("wanted first entry %q, got %q", tc.expectedFirst, first)
+			}
+			if last := strings.Join(lr.Backlog[len(lr.Backlog)-1].Leveled.messages, "\n"); last != tc.expectedLast {
+				t.Errorf("wanted last entry %q, got %q", tc.expectedLast, last)
+			}
+			for i, entry := range lr.Backlog {
+				// If we skip messages and are reading oldest first, adapt the
+				// id to the expected position
+				if tc.pos != 0 && tc.direction == ReadDirectionAfter {
+					i = tc.pos + i
+				}
+				if tc.count != BacklogAllAvailable && tc.pos != 0 && tc.direction == ReadDirectionBefore {
+					// Limit the negative offset to 0
+					i = max(0, tc.pos-tc.count) + i
+				}
+				want := fmt.Sprintf("test %d", i)
+				got := strings.Join(entry.Leveled.messages, "\n")
+				if want != got {
+					t.Errorf("wanted entry %q, got %q", want, got)
+				}
+			}
+		})
+	}
+}