diff --git a/r13/sources/cxx-stl/llvm-libc++/include/cmath b/r13/sources/cxx-stl/llvm-libc++/include/cmath
index b3e95940..86f037a1 100644
--- a/r13/sources/cxx-stl/llvm-libc++/include/cmath
+++ b/r13/sources/cxx-stl/llvm-libc++/include/cmath
@@ -310,11 +310,18 @@ long double    truncl(long double x);
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
+#ifndef signbit
 using ::signbit;
+#endif
+#ifndef fpclassify
 using ::fpclassify;
+#endif
+#ifndef isfinite
 using ::isfinite;
+#endif
 using ::isinf;
 using ::isnan;
+#ifndef isnormal
 using ::isnormal;
 using ::isgreater;
 using ::isgreaterequal;
@@ -323,11 +330,12 @@ using ::islessequal;
 using ::islessgreater;
 using ::isunordered;
 using ::isunordered;
+#endif
 
 using ::float_t;
 using ::double_t;
 
-#ifndef _AIX
+#if !defined(_AIX) && !defined(__BIONIC__)
 using ::abs;
 #endif