diff --git a/clang/lib/AST/FormatString.cpp b/clang/lib/AST/FormatString.cpp
--- a/clang/lib/AST/FormatString.cpp
+++ b/clang/lib/AST/FormatString.cpp
@@ -848,6 +848,8 @@
       }
 
       switch (CS.getKind()) {
+        case ConversionSpecifier::bArg:
+        case ConversionSpecifier::BArg:
         case ConversionSpecifier::dArg:
         case ConversionSpecifier::DArg:
         case ConversionSpecifier::iArg:
diff --git a/clang/test/Sema/format-strings.c b/clang/test/Sema/format-strings.c
--- a/clang/test/Sema/format-strings.c
+++ b/clang/test/Sema/format-strings.c
@@ -304,6 +304,7 @@
   printf("%qp", (void *)0); // expected-warning{{length modifier 'q' results in undefined behavior or no effect with 'p' conversion specifier}}
   printf("hhX %hhX", (unsigned char)10); // no-warning
   printf("llX %llX", (long long) 10); // no-warning
+  printf("%lb %lB", (long) 10, (long) 10); // no-warning
   printf("%llb %llB", (long long) 10, (long long) 10); // no-warning
   // This is fine, because there is an implicit conversion to an int.
   printf("%d", (unsigned char) 10); // no-warning