diff --git a/lib/Target/CBackend/CBackend.cpp b/lib/Target/CBackend/CBackend.cpp
index bdc8b8d6500..c4d8c464837 100644
--- a/lib/Target/CBackend/CBackend.cpp
+++ b/lib/Target/CBackend/CBackend.cpp
@@ -573,7 +573,7 @@ void CWriter::printConstant(Constant *CPV) {
         char Buffer[100];
 
         DHex.d = FPC->getValue();
-        sprintf(Buffer, "0x%llx", DHex.ll);
+        sprintf(Buffer, "0x%llx", (unsigned long long)DHex.ll);
 
         std::string Num(&Buffer[0], &Buffer[6]);
         unsigned long Val = strtoul(Num.c_str(), 0, 16);
diff --git a/lib/Target/CBackend/Writer.cpp b/lib/Target/CBackend/Writer.cpp
index bdc8b8d6500..c4d8c464837 100644
--- a/lib/Target/CBackend/Writer.cpp
+++ b/lib/Target/CBackend/Writer.cpp
@@ -573,7 +573,7 @@ void CWriter::printConstant(Constant *CPV) {
         char Buffer[100];
 
         DHex.d = FPC->getValue();
-        sprintf(Buffer, "0x%llx", DHex.ll);
+        sprintf(Buffer, "0x%llx", (unsigned long long)DHex.ll);
 
         std::string Num(&Buffer[0], &Buffer[6]);
         unsigned long Val = strtoul(Num.c_str(), 0, 16);