diff --git a/CHANGELOG.md b/CHANGELOG.md
index 74a7834..2c58b41 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- A quoted mapping key may now have a space before its `:` (`"key" : value`). A plain key
+  consumes the space before the colon into the scalar, but a quoted key stops at its closing
+  quote, leaving the space, and the implicit-key check looked only at the immediate next
+  character. It now looks past spaces for the colon, as the spec allows. Quoted keys with no
+  space, quoted values, and plain keys are unaffected. Lifts official test-suite parse-level
+  conformance from 238/333 (71.5%) to 240/333 (72.1%).
 - A block mapping pair after the first may now carry an anchor or tag on its key
   (`k: 1` / `&b key2: 2`). The first pair's key properties were consumed when the mapping was
   entered, but later pairs were not, so an anchored key past the first failed with
diff --git a/Sources/Parsing/Scanner.Helpers.swift b/Sources/Parsing/Scanner.Helpers.swift
index 518a2ae..d8ee0e0 100644
--- a/Sources/Parsing/Scanner.Helpers.swift
+++ b/Sources/Parsing/Scanner.Helpers.swift
@@ -291,6 +291,18 @@ extension PureYAML.Parsing.Scanner {
         state.reader.peek() == ":" && shouldEndPlainScalarAtMappingValue(state: state)
     }
 
+    /// Whether a mapping-value indicator (`: ` or `:` at line end) follows, allowing spaces before
+    /// the colon. Used after a quoted scalar, where the reader stops at the closing quote and any
+    /// separating spaces remain, unlike a plain scalar that ends at the colon itself.
+    func isAtMappingValueIndicatorAfterSpaces(state: State) -> Bool {
+        var offset = 0
+        while state.reader.peek(offset: offset) == " " {
+            offset += 1
+        }
+        return state.reader.peek(offset: offset) == ":"
+            && isBlockMappingValueBoundary(state.reader.peek(offset: offset + 1))
+    }
+
     @discardableResult
     func appendMappingKeyIfNeeded(
         start: PureYAML.Parsing.Mark,
diff --git a/Sources/Parsing/Scanner.swift b/Sources/Parsing/Scanner.swift
index b30c6a3..9881984 100644
--- a/Sources/Parsing/Scanner.swift
+++ b/Sources/Parsing/Scanner.swift
@@ -288,7 +288,12 @@ extension PureYAML.Parsing.Scanner {
             throw PureYAML.Parsing.ParseError.unterminatedQuotedString(line: start.line)
         }
         state.reader.advance()
-        appendMappingKeyIfNeeded(start: start, state: &state)
+        // Unlike a plain scalar (which consumes the space before a `:` into itself), a quoted scalar
+        // stops at its closing quote, so the reader sits at any spaces before a `:`. A space between
+        // an implicit key and its mapping-value indicator is allowed, so look past them.
+        if isAtMappingValueIndicatorAfterSpaces(state: state) {
+            state.append(.mappingKey, mark: start, endMark: start)
+        }
         state.append(.scalar(value: value, style: style), mark: start, endMark: state.reader.mark)
     }
 
diff --git a/Tests/QuotedKeyTests.swift b/Tests/QuotedKeyTests.swift
new file mode 100644
index 0000000..4a3ec83
--- /dev/null
+++ b/Tests/QuotedKeyTests.swift
@@ -0,0 +1,19 @@
+@testable import PureYAML
+import Testing
+
+@Suite("Quoted mapping keys")
+struct QuotedKeyTests {
+    @Test("A quoted key may have a space before its colon")
+    func test_quotedKeyWithSpaceBeforeColon() throws {
+        let expected = PureYAML.Model.Value.mapping(.init([.init(key: "key", value: .string("value"))]))
+        #expect(try PureYAML.parse("\"key\" : value\n") == expected)
+        #expect(try PureYAML.parse("'key' : value\n") == expected)
+        // The no-space form keeps working.
+        #expect(try PureYAML.parse("\"key\": value\n") == expected)
+    }
+
+    @Test("A quoted value, with or without a preceding space, is unaffected")
+    func test_quotedValueUnaffected() throws {
+        #expect(try PureYAML.parse("k: \"quoted value\"\n") == .mapping(.init([.init(key: "k", value: .string("quoted value"))])))
+    }
+}