diff --git a/libc/include/stdlib.h b/libc/include/stdlib.h
index 1ae3c6e..944d72b 100644
--- a/libc/include/stdlib.h
+++ b/libc/include/stdlib.h
@@ -172,12 +172,17 @@
 #include <bits/fortify/stdlib.h>
 #endif
 
+#if __ANDROID_API__ >= __ANDROID_API_K__
+int abs(int __x) __attribute_const__ __INTRODUCED_IN(19);
+long labs(long __x) __attribute_const__ __INTRODUCED_IN(19);
+long long llabs(long long __x) __attribute_const__ __INTRODUCED_IN(19);
+#else
+// Implemented as static inlines before 19.
+#endif
+
 #if __ANDROID_API__ >= __ANDROID_API_L__
 float strtof(const char* __s, char** __end_ptr) __INTRODUCED_IN(21);
 double atof(const char* __s) __attribute_pure__ __INTRODUCED_IN(21);
-int abs(int __x) __attribute_const__ __INTRODUCED_IN(21);
-long labs(long __x) __attribute_const__ __INTRODUCED_IN(21);
-long long llabs(long long __x) __attribute_const__ __INTRODUCED_IN(21);
 int rand(void) __INTRODUCED_IN(21);
 void srand(unsigned int __seed) __INTRODUCED_IN(21);
 long random(void) __INTRODUCED_IN(21);