diff --git a/lib/Analysis/FormatString.cpp b/lib/Analysis/FormatString.cpp
index c1b5ea8..9a86390 100644
--- a/lib/Analysis/FormatString.cpp
+++ b/lib/Analysis/FormatString.cpp
@@ -225,10 +225,10 @@
             break;
           case BuiltinType::Char_S:
           case BuiltinType::SChar:
-            return T == C.UnsignedCharTy;
+            return T == C.SignedCharTy;
           case BuiltinType::Char_U:
           case BuiltinType::UChar:
-            return T == C.SignedCharTy;
+            return T == C.UnsignedCharTy;
           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 35210c3..83f96ff 100644
--- a/test/Sema/format-strings.c
+++ b/test/Sema/format-strings.c
@@ -363,3 +363,12 @@
 void rdar9612060(void) {
   printf("%s", 2); // expected-warning{{conversion specifies type 'char *' but the argument has type 'int'}}
 }
+
+void check_char(unsigned char x, signed char y) {
+  printf("%c", y); // no-warning
+  printf("%hhu", x); // no-warning
+  printf("%hhi", y); // no-warning
+  printf("%hhi", x); // expected-warning{{conversion specifies type 'signed char' but the argument has type 'unsigned char'}}
+  printf("%c", x); // no-warning
+  printf("%hhu", y); // expected-warning{{conversion specifies type 'unsigned char' but the argument has type 'signed char'}}
+}