diff --git a/Android.bp b/Android.bp
index 33b21ec..04831a4 100755
--- a/Android.bp
+++ b/Android.bp
@@ -5,15 +5,23 @@
         "-Werror",
         "-Wno-unused-parameter",
         "-O2",
+        "-ffp-contract=fast",
+        "-fno-math-errno",
+
+        // bionic configuration.
+
         // We're actually implementing bionic here, so we don't want <math.h>
         // to try to be helpful by renaming long double routines.
         "-D__BIONIC_LP32_USE_LONG_DOUBLE",
-        "-DWANT_ROUNDING=0",
-        "-DWANT_ERRNO=0",
-        "-DWANT_VMATH=0",
         "-DFLT_EVAL_METHOD=0",
-        "-ffp-contract=fast",
-        "-fno-math-errno",
+
+        // arm-optimized-routines configuration.
+
+        // BSD libm doesn't set errno, and bionic was based on the BSDs.
+        // https://github.com/ARM-software/optimized-routines/issues/16#issuecomment-572009659
+        "-DWANT_ERRNO=0",
+        // TODO: we will want the SVE code in future, but it's not ready yet.
+        "-DWANT_VMATH=0",
     ],
     local_include_dirs: ["math/include"],
 }