diff --git a/libc/include/string.h b/libc/include/string.h
index 631b3dd..164146d 100644
--- a/libc/include/string.h
+++ b/libc/include/string.h
@@ -58,8 +58,11 @@
 char* __strchr_chk(const char*, int, size_t) __INTRODUCED_IN(18);
 #if defined(__USE_GNU)
 #if defined(__cplusplus)
+/* The versioner doesn't handle C++ blocks yet, so manually guarded. */
+#if __ANDROID_API__ >= 24
 extern "C++" char* strchrnul(char*, int) __RENAME(strchrnul) __attribute_pure__ __INTRODUCED_IN(24);
 extern "C++" const char* strchrnul(const char*, int) __RENAME(strchrnul) __attribute_pure__ __INTRODUCED_IN(24);
+#endif  /* __ANDROID_API__ >= 24 */
 #else
 char* strchrnul(const char*, int) __attribute_pure__ __INTRODUCED_IN(24);
 #endif
@@ -125,8 +128,11 @@
  * It doesn't modify its argument, and in C++ it's const-correct.
  */
 #if defined(__cplusplus)
+/* The versioner doesn't handle C++ blocks yet, so manually guarded. */
+#if __ANDROID_API__ >= 23
 extern "C++" char* basename(char*) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
 extern "C++" const char* basename(const char*) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
+#endif  /* __ANDROID_API__ >= 23 */
 #else
 char* basename(const char*) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
 #endif