diff --git a/Sources/SwiftDiagnostics/GroupedDiagnostics.swift b/Sources/SwiftDiagnostics/GroupedDiagnostics.swift
index 25584741ee6..02ffd75b847 100644
--- a/Sources/SwiftDiagnostics/GroupedDiagnostics.swift
+++ b/Sources/SwiftDiagnostics/GroupedDiagnostics.swift
@@ -207,7 +207,7 @@ extension GroupedDiagnostics {
 
         // Display file/line/column and diagnostic text for the primary diagnostic.
         prefixString =
-          "\(location.file):\(location.line):\(location.column): \(diagnosticDecorator.decorateDiagnosticMessage(primaryDiag.diagMessage))\n"
+          "\(location.presumedFile):\(location.presumedLine):\(location.column): \(diagnosticDecorator.decorateDiagnosticMessage(primaryDiag.diagMessage))\n"
 
         // If the primary diagnostic source file is not the same as the root source file, we're pointing into a generated buffer.
         // Provide a link back to the original source file where this generated buffer occurred, so it's easy to find if
diff --git a/Tests/SwiftDiagnosticsTest/GroupDiagnosticsFormatterTests.swift b/Tests/SwiftDiagnosticsTest/GroupDiagnosticsFormatterTests.swift
index 3c4e6fd18ae..14aeff3ee5d 100644
--- a/Tests/SwiftDiagnosticsTest/GroupDiagnosticsFormatterTests.swift
+++ b/Tests/SwiftDiagnosticsTest/GroupDiagnosticsFormatterTests.swift
@@ -60,6 +60,31 @@ extension GroupedDiagnostics {
 }
 
 final class GroupedDiagnosticsFormatterTests: XCTestCase {
+  func testSourceLocations() {
+    var group = GroupedDiagnostics()
+
+    // Main source file.
+    _ = group.addTestFile(
+      """
+      #sourceLocation(file: "other.swift", line: 123)
+      let pi = 3.14159 x
+      """,
+      displayName: "main.swift",
+      diagnosticDescriptors: []
+    )
+    let annotated = DiagnosticsFormatter.annotateSources(in: group)
+    assertStringsEqualWithDiff(
+      annotated,
+      """
+      other.swift:123:17: error: consecutive statements on a line must be separated by newline or ';'
+      1 │ #sourceLocation(file: "other.swift", line: 123)
+      2 │ let pi = 3.14159 x
+        │                 ╰─ error: consecutive statements on a line must be separated by newline or ';'
+
+      """
+    )
+  }
+
   func testGroupingForMacroExpansion() {
     var group = GroupedDiagnostics()