diff --git a/libc/src/ctype/isascii.h b/libc/src/ctype/isascii.h
--- a/libc/src/ctype/isascii.h
+++ b/libc/src/ctype/isascii.h
@@ -9,6 +9,8 @@
 #ifndef LLVM_LIBC_SRC_CTYPE_ISASCII_H
 #define LLVM_LIBC_SRC_CTYPE_ISASCII_H
 
+#undef isascii
+
 namespace __llvm_libc {
 
 int isascii(int c);
diff --git a/libc/test/src/ctype/isascii_test.cpp b/libc/test/src/ctype/isascii_test.cpp
--- a/libc/test/src/ctype/isascii_test.cpp
+++ b/libc/test/src/ctype/isascii_test.cpp
@@ -6,10 +6,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "src/ctype/isascii.h"
-
 #include "utils/UnitTest/Test.h"
 
+#include "src/ctype/isascii.h"
+
 TEST(IsAscii, DefaultLocale) {
   // Loops through all characters, verifying that ascii characters
   //    (which are all 7 bit unsigned integers)
diff --git a/libc/utils/UnitTest/FuchsiaTest.h b/libc/utils/UnitTest/FuchsiaTest.h
--- a/libc/utils/UnitTest/FuchsiaTest.h
+++ b/libc/utils/UnitTest/FuchsiaTest.h
@@ -10,11 +10,5 @@
 #define LLVM_LIBC_UTILS_UNITTEST_FUCHSIATEST_H
 
 #include <zxtest/zxtest.h>
-// isascii is being undef'd because Fuchsia's headers define a macro for
-// isascii. that macro causes errors when isascii_test.cpp references
-// __llvm_libc::isascii since the macro is applied first.
-#ifdef isascii
-#undef isascii
-#endif
 
 #endif // LLVM_LIBC_UTILS_UNITTEST_FUCHSIATEST_H