diff --git a/lib/Rewrite/HTMLRewrite.cpp b/lib/Rewrite/HTMLRewrite.cpp
index 342b0e6..cf1c779 100644
--- a/lib/Rewrite/HTMLRewrite.cpp
+++ b/lib/Rewrite/HTMLRewrite.cpp
@@ -43,8 +43,18 @@
   // Include the whole end token in the range.
   EOffset += Lexer::MeasureTokenLength(E, R.getSourceMgr(), R.getLangOpts());
 
+  llvm::StringRef FileName;
+  std::string ErrorStr;
+  const char *BufferStart = SM.getBufferData(FID, FileName, ErrorStr).first;
+  if (!BufferStart) {
+    // FIXME: Add a diagnostic object somewhere?
+    fprintf(stderr, "error: cannot open file '%s': %s\n", 
+            FileName.str().c_str(), ErrorStr.c_str());
+    return;
+  }
+  
   HighlightRange(R.getEditBuffer(FID), BOffset, EOffset,
-                 SM.getBufferData(FID).first, StartTag, EndTag);
+                 BufferStart, StartTag, EndTag);
 }
 
 /// HighlightRange - This is the same as the above method, but takes
diff --git a/lib/Rewrite/Rewriter.cpp b/lib/Rewrite/Rewriter.cpp
index 9744496..84c0979 100644
--- a/lib/Rewrite/Rewriter.cpp
+++ b/lib/Rewrite/Rewriter.cpp
@@ -165,7 +165,17 @@
     return I->second;
   I = RewriteBuffers.insert(I, std::make_pair(FID, RewriteBuffer()));
 
-  std::pair<const char*, const char*> MB = SourceMgr->getBufferData(FID);
+  llvm::StringRef FileName;
+  std::string ErrorStr;
+  
+  std::pair<const char*, const char*> MB
+    = SourceMgr->getBufferData(FID, FileName, ErrorStr);
+  if (!MB.first) {
+    // FIXME: Add a diagnostic object somewhere?
+    fprintf(stderr, "error: cannot open file '%s': %s\n", 
+            FileName.str().c_str(), ErrorStr.c_str());
+  }
+  
   I->second.Initialize(MB.first, MB.second);
 
   return I->second;