diff --git a/libc/src/ctype/isblank.cpp b/libc/src/ctype/isblank.cpp
index b29d19aef2f1..1c3061379b29 100644
--- a/libc/src/ctype/isblank.cpp
+++ b/libc/src/ctype/isblank.cpp
@@ -1,22 +1,22 @@
 //===-- Implementation of isblank------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "src/ctype/isblank.h"
 
 #include "src/__support/common.h"
 
 namespace __llvm_libc {
 
 // TODO: Currently restricted to default locale.
 // These should be extended using locale information.
 LLVM_LIBC_FUNCTION(int, isblank, (int c)) {
-  const unsigned char ch = c;
+  const unsigned char ch = static_cast<char>(c);
   return ch == ' ' || ch == '\t';
 }
 
 } // namespace __llvm_libc
diff --git a/libc/src/ctype/iscntrl.cpp b/libc/src/ctype/iscntrl.cpp
index 8962bcae0a84..b061199c47ec 100644
--- a/libc/src/ctype/iscntrl.cpp
+++ b/libc/src/ctype/iscntrl.cpp
@@ -1,22 +1,22 @@
 //===-- Implementation of iscntrl------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "src/ctype/iscntrl.h"
 
 #include "src/__support/common.h"
 
 namespace __llvm_libc {
 
 // TODO: Currently restricted to default locale.
 // These should be extended using locale information.
 LLVM_LIBC_FUNCTION(int, iscntrl, (int c)) {
-  const unsigned char ch = c;
+  const unsigned char ch = static_cast<char>(c);
   return ch < 0x20 || ch == 0x7f;
 }
 
 } // namespace __llvm_libc