Index: lib/StaticAnalyzer/Core/HTMLDiagnostics.cpp
===================================================================
--- lib/StaticAnalyzer/Core/HTMLDiagnostics.cpp
+++ lib/StaticAnalyzer/Core/HTMLDiagnostics.cpp
@@ -321,7 +321,9 @@
     return {};
 
   // Add CSS, header, and footer.
-  const FileEntry* Entry = SMgr.getFileEntryForID(FileIDs[0]);
+  FileID FID =
+      path.back()->getLocation().asLocation().getExpansionLoc().getFileID();
+  const FileEntry* Entry = SMgr.getFileEntryForID(FID);
   FinalizeHTML(D, R, SMgr, path, FileIDs[0], Entry, declName);
 
   std::string file;
Index: test/Coverage/html-multifile-diagnostics.c
===================================================================
--- test/Coverage/html-multifile-diagnostics.c
+++ test/Coverage/html-multifile-diagnostics.c
@@ -4,6 +4,8 @@
 
 // REQUIRES: staticanalyzer
 
+// CHECK: <!-- FILENAME html-multifile-diagnostics.h -->
+
 // CHECK: <h3>Annotated Source Code</h3>
 
 // Make sure it's generated as multi-file HTML output