diff --git a/clang/lib/StaticAnalyzer/Core/IssueHash.cpp b/clang/lib/StaticAnalyzer/Core/IssueHash.cpp
index c352f12111ff..bd5c81179adc 100644
--- a/clang/lib/StaticAnalyzer/Core/IssueHash.cpp
+++ b/clang/lib/StaticAnalyzer/Core/IssueHash.cpp
@@ -132,8 +132,11 @@ static std::string NormalizeLine(const SourceManager &SM, FullSourceLoc &L,
 
   StringRef Str = GetNthLineOfFile(SM.getBuffer(L.getFileID(), L),
                                    L.getExpansionLineNumber());
-  unsigned col = Str.find_first_not_of(Whitespaces);
-  col++;
+  StringRef::size_type col = Str.find_first_not_of(Whitespaces);
+  if (col == StringRef::npos)
+    col = 1; // The line only contains whitespace.
+  else
+    col++;
   SourceLocation StartOfLine =
       SM.translateLineCol(SM.getFileID(L), L.getExpansionLineNumber(), col);
   llvm::MemoryBuffer *Buffer =