diff --git a/Sources/Parsing/Scanner.Indentation.swift b/Sources/Parsing/Scanner.Indentation.swift
index 259fa7d..fc101c6 100644
--- a/Sources/Parsing/Scanner.Indentation.swift
+++ b/Sources/Parsing/Scanner.Indentation.swift
@@ -11,6 +11,22 @@ extension PureYAML.Parsing.Scanner {
         let end = state.reader.mark
         let current = state.indentation.last ?? 0
         let wasInBlockScalar = state.blockScalarIndentation != nil
+
+        // A document marker (`---` / `...`) at column 0 ends an active block scalar rather than
+        // being its content. Close the scalar's indentation here, dedenting back to the document
+        // level, so the marker is then scanned balanced at the document level. Without this the
+        // scalar's indent lingers past the marker and surfaces later as a stray dedent plus a
+        // phantom empty node (the marker still ends the document, but the structure is unbalanced).
+        if state.blockScalarIndentation != nil, width == 0, isAtDocumentMarker(state.reader) {
+            state.blockScalarIndentation = nil
+            state.blockScalarContentPrefix = ""
+            while state.indentation.count > 1 {
+                state.indentation.removeLast()
+                state.append(.dedent(width: state.indentation.last ?? 0), mark: end, endMark: end)
+            }
+            return
+        }
+
         if consumeBlockScalarContentIndentation(width: width, state: &state) {
             return
         }
diff --git a/Tests/BlockScalarDocumentBoundaryTests.swift b/Tests/BlockScalarDocumentBoundaryTests.swift
new file mode 100644
index 0000000..452f5cf
--- /dev/null
+++ b/Tests/BlockScalarDocumentBoundaryTests.swift
@@ -0,0 +1,27 @@
+@testable import PureYAML
+import Testing
+
+/// A root block scalar whose content runs to column 0 is ended by a document marker (`...` or
+/// `---`), not continued into it. The scalar's indentation is closed at the marker, so the stream
+/// stays balanced: no stray dedent and no phantom empty document afterward.
+@Suite("Block scalar ended by document boundary")
+struct BlockScalarDocumentBoundaryTests {
+    @Test("A `...` ends a root block scalar, yielding a single document")
+    func test_terminatedByDocumentEnd() throws {
+        let documents = try PureYAML.parseStream("--- |\n%!PS\n...\n").map(\.value)
+        #expect(documents == [.string("%!PS\n")])
+    }
+
+    @Test("A `---` ends a root block scalar and starts the next document")
+    func test_terminatedByNextDocumentStart() throws {
+        let documents = try PureYAML.parseStream("--- |\n%!PS\n--- next\n").map(\.value)
+        #expect(documents == [.string("%!PS\n"), .string("next")])
+    }
+
+    @Test("Suite case W4TN: a directive, a root literal block scalar, then a comment-only document")
+    func test_w4tnShape() throws {
+        let yaml = "%YAML 1.2\n--- |\n%!PS-Adobe-2.0\n...\n%YAML 1.2\n---\n# Empty\n...\n"
+        let documents = try PureYAML.parseStream(yaml).map(\.value)
+        #expect(documents == [.string("%!PS-Adobe-2.0\n"), .null])
+    }
+}