diff --git a/lib/Analysis/FormatString.cpp b/lib/Analysis/FormatString.cpp
index ab69c06..f776c89 100644
--- a/lib/Analysis/FormatString.cpp
+++ b/lib/Analysis/FormatString.cpp
@@ -265,10 +265,9 @@
             break;
           case BuiltinType::Char_S:
           case BuiltinType::SChar:
-            return T == C.UnsignedCharTy;
           case BuiltinType::Char_U:
           case BuiltinType::UChar:                    
-            return T == C.SignedCharTy;
+            return T == C.UnsignedCharTy || T == C.SignedCharTy;
           case BuiltinType::Short:
             return T == C.UnsignedShortTy;
           case BuiltinType::UShort:
diff --git a/test/Sema/format-strings.c b/test/Sema/format-strings.c
index 5d8e4cb..1f9acd4 100644
--- a/test/Sema/format-strings.c
+++ b/test/Sema/format-strings.c
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -fsyntax-only -verify -Wformat-nonliteral -isystem %S/Inputs %s
+// RUN: %clang_cc1 -fsyntax-only -verify -Wformat-nonliteral -isystem %S/Inputs -fno-signed-char %s
 
 #define __need_wint_t
 #include <stdarg.h>
@@ -530,3 +531,8 @@
 void test_unused_system_args(int x) {
   PRINT1("%d\n", x); // no-warning{{extra argument is system header is OK}}
 }
+
+void pr12761(char c) {
+  // This should not warn even with -fno-signed-char.
+  printf("%hhx", c);
+}