diff --git a/Sources/Parsing/LibYAML.Scanner.swift b/Sources/Parsing/LibYAML.Scanner.swift
index fc75c99..bff0fa6 100644
--- a/Sources/Parsing/LibYAML.Scanner.swift
+++ b/Sources/Parsing/LibYAML.Scanner.swift
@@ -37,7 +37,17 @@ extension PureYAML.Parsing.LibYAML {
         mutating func staleSimpleKeys() throws {
             for index in simpleKeys.indices {
                 let key = simpleKeys[index]
-                guard key.possible, key.mark.line < mark.line || key.mark.index + 1024 < mark.index else {
+                guard key.possible else {
+                    continue
+                }
+                // A block-context key (index 0) is single-line. A flow-context key
+                // (index >= 1) may be separated from its ':' by line breaks under
+                // YAML 1.2, so a new line alone does not invalidate it; both remain
+                // bounded to 1024 characters. libyaml invalidates every key on a new
+                // line, which wrongly rejects multi-line flow keys.
+                let tooFarBack = key.mark.index + 1024 < mark.index
+                let stale = index == 0 ? (key.mark.line < mark.line || tooFarBack) : tooFarBack
+                guard stale else {
                     continue
                 }
                 if key.required {
diff --git a/Tests/CanonicalEventConformanceTests.swift b/Tests/CanonicalEventConformanceTests.swift
index 93323c5..f69705a 100644
--- a/Tests/CanonicalEventConformanceTests.swift
+++ b/Tests/CanonicalEventConformanceTests.swift
@@ -21,13 +21,11 @@ struct CanonicalEventConformanceTests {
         // itself handles.
         //
         // false-rejects (parseEvents throws on valid input, as libyaml does)
-        "2JQS", "2SXE", "4ABK", "4MUZ/00", "4MUZ/01", "4MUZ/02", "58MP",
-        "5MUD", "5T43", "6BCT", "6CA3", "6M2F", "7Z25", "8XYN", "96NN/00",
-        "96NN/01", "9SA2", "A2M4", "CFD4", "DBG4", "DK3J", "DK95/00",
-        "DK95/04", "FP8R", "FRK4", "HM87/00", "HWV9", "K3WX", "M2N8/00",
-        "M7A3", "NHX8", "NJ66", "NKF9", "Q5MG", "QT73",
-        "R4YG", "S3PD", "SM9W/01", "UKK6/00", "UT92", "VJP3/01", "W4TN", "W5VH",
-        "Y79Y/001", "Y79Y/010",
+        "2JQS", "2SXE", "4ABK", "58MP", "5T43", "6BCT", "6CA3", "6M2F", "7Z25",
+        "8XYN", "96NN/00", "96NN/01", "A2M4", "CFD4", "DBG4", "DK3J", "DK95/00",
+        "DK95/04", "FP8R", "FRK4", "HM87/00", "HWV9", "M2N8/00", "M7A3", "NHX8",
+        "NKF9", "Q5MG", "QT73", "R4YG", "S3PD", "SM9W/01", "UKK6/00", "W4TN",
+        "W5VH", "Y79Y/001", "Y79Y/010",
         // wrong event stream: the port matches libyaml but both deviate from the
         // canonical events (libyaml quirks to be surpassed).
         "652Z", "HM87/01", "JEF9/02", "Y2GN",