diff --git a/lib/Bytecode/Writer/Writer.cpp b/lib/Bytecode/Writer/Writer.cpp
index ad2dbd0fcc1..9862391b3ac 100644
--- a/lib/Bytecode/Writer/Writer.cpp
+++ b/lib/Bytecode/Writer/Writer.cpp
@@ -1071,7 +1071,7 @@ void BytecodeWriter::outputSymbolTable(const SymbolTable &MST) {
     if (I == End) continue;  // Don't mess with an absent type...
 
     // Write the number of values in this plane
-    output_vbr(PI->second.size());
+    output_vbr((unsigned)PI->second.size());
 
     // Write the slot number of the type for this plane
     Slot = Table.getSlot(PI->first);