diff --git a/lib/Target/CBackend/CBackend.cpp b/lib/Target/CBackend/CBackend.cpp
index 6bc3c504344..ce7f4c8ff24 100644
--- a/lib/Target/CBackend/CBackend.cpp
+++ b/lib/Target/CBackend/CBackend.cpp
@@ -834,6 +834,7 @@ bool CWriter::doInitialization(Module &M) {
 
   // Ensure that all structure types have names...
   Mang = new Mangler(M);
+  Mang->markCharUnacceptable('.');
 
   // get declaration for alloca
   Out << "/* Provide Declarations */\n";
diff --git a/lib/Target/CBackend/Writer.cpp b/lib/Target/CBackend/Writer.cpp
index 6bc3c504344..ce7f4c8ff24 100644
--- a/lib/Target/CBackend/Writer.cpp
+++ b/lib/Target/CBackend/Writer.cpp
@@ -834,6 +834,7 @@ bool CWriter::doInitialization(Module &M) {
 
   // Ensure that all structure types have names...
   Mang = new Mangler(M);
+  Mang->markCharUnacceptable('.');
 
   // get declaration for alloca
   Out << "/* Provide Declarations */\n";