diff --git a/lib/MC/MCAsmStreamer.cpp b/lib/MC/MCAsmStreamer.cpp
index 60c737a..4c2f128 100644
--- a/lib/MC/MCAsmStreamer.cpp
+++ b/lib/MC/MCAsmStreamer.cpp
@@ -58,7 +58,7 @@
   virtual void EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
                                 unsigned Pow2Alignment, bool IsLocal);
 
-  virtual void EmitZerofill(MCSection *Section, MCSymbol *Symbol = NULL,
+  virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
                             unsigned Size = 0, unsigned Pow2Alignment = 0);
 
   virtual void EmitBytes(const StringRef &Data);
@@ -189,7 +189,7 @@
   OS << '\n';
 }
 
-void MCAsmStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
+void MCAsmStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
                                  unsigned Size, unsigned Pow2Alignment) {
   // Note: a .zerofill directive does not switch sections.
   OS << ".zerofill ";
diff --git a/lib/MC/MCMachOStreamer.cpp b/lib/MC/MCMachOStreamer.cpp
index f5887db..7e8a715 100644
--- a/lib/MC/MCMachOStreamer.cpp
+++ b/lib/MC/MCMachOStreamer.cpp
@@ -107,7 +107,7 @@
   virtual void EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
                                 unsigned Pow2Alignment, bool IsLocal);
 
-  virtual void EmitZerofill(MCSection *Section, MCSymbol *Symbol = NULL,
+  virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
                             unsigned Size = 0, unsigned Pow2Alignment = 0);
 
   virtual void EmitBytes(const StringRef &Data);
@@ -273,7 +273,7 @@
   llvm_unreachable("FIXME: Not yet implemented!");
 }
 
-void MCMachOStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
+void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
                                    unsigned Size, unsigned Pow2Alignment) {
   llvm_unreachable("FIXME: Not yet implemented!");
 }
diff --git a/lib/MC/MCNullStreamer.cpp b/lib/MC/MCNullStreamer.cpp
index 61a9d49..14534ed 100644
--- a/lib/MC/MCNullStreamer.cpp
+++ b/lib/MC/MCNullStreamer.cpp
@@ -46,7 +46,7 @@
     virtual void EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
                                   unsigned Pow2Alignment, bool IsLocal) {}
 
-    virtual void EmitZerofill(MCSection *Section, MCSymbol *Symbol = NULL,
+    virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
                               unsigned Size = 0, unsigned Pow2Alignment = 0) {}
 
     virtual void EmitBytes(const StringRef &Data) {}