diff --git a/lib/System/Path.cpp b/lib/System/Path.cpp
index 4c965db7223..72bd7ad6f04 100644
--- a/lib/System/Path.cpp
+++ b/lib/System/Path.cpp
@@ -55,7 +55,7 @@ LLVMFileType
 sys::IdentifyFileType(const char *magic, unsigned length) {
   assert(magic && "Invalid magic number string");
   assert(length >=4 && "Invalid magic number length");
-  switch (magic[0]) {
+  switch ((unsigned char)magic[0]) {
     case 0xDE:  // 0x0B17C0DE = BC wraper
       if (magic[1] == (char)0xC0 && magic[2] == (char)0x17 &&
           magic[3] == (char)0x0B)
diff --git a/test/Assembler/bcwrap.ll b/test/Assembler/bcwrap.ll
new file mode 100644
index 00000000000..859dc4bc80f
--- /dev/null
+++ b/test/Assembler/bcwrap.ll
@@ -0,0 +1,9 @@
+; RUN: llvm-as < %s > %t
+; RUN: llvm-nm %t | grep foo
+; test for isBitcodeFile, llvm-nm must read from a file for this test
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+target triple = "i686-apple-darwin9.2.2"
+
+define i32 @foo() {
+  ret i32 0
+}