diff --git a/lib/Basic/SourceLoc.cpp b/lib/Basic/SourceLoc.cpp
index 4649e58dfddab..5af45683505f9 100644
--- a/lib/Basic/SourceLoc.cpp
+++ b/lib/Basic/SourceLoc.cpp
@@ -797,11 +797,11 @@ static bool isBeforeInSource(
   SourceLoc firstLocInLCA = firstMismatch == firstAncestors.end()
       ? firstLoc
       : sourceMgr.getGeneratedSourceInfo(*firstMismatch)
-          ->originalSourceRange.getStart();
+          ->originalSourceRange.getEnd();
   SourceLoc secondLocInLCA = secondMismatch == secondAncestors.end()
       ? secondLoc
       : sourceMgr.getGeneratedSourceInfo(*secondMismatch)
-          ->originalSourceRange.getStart();
+          ->originalSourceRange.getEnd();
   return sourceMgr.isBeforeInBuffer(firstLocInLCA, secondLocInLCA) ||
     (allowEqual && firstLocInLCA == secondLocInLCA);
 }
diff --git a/test/stdlib/Observation/Observable.swift b/test/stdlib/Observation/Observable.swift
index 50c140f15640e..4cd0f2f9dca0e 100644
--- a/test/stdlib/Observation/Observable.swift
+++ b/test/stdlib/Observation/Observable.swift
@@ -215,6 +215,16 @@ class RecursiveOuter {
 class GuardedAvailability {
 }
 
+@Observable class TestASTScopeLCA {
+  // Make sure ASTScope unqualified lookup can find local variables
+  // inside initial values with closures when accessor macros are
+  // involved.
+  var state : Bool = {
+    let value = true
+    return value
+  }()
+}
+
 @main
 struct Validator {
   @MainActor