diff --git a/std/experimental/allocator/mallocator.d b/std/experimental/allocator/mallocator.d
index 4266ea96e89..862a831c8ee 100644
--- a/std/experimental/allocator/mallocator.d
+++ b/std/experimental/allocator/mallocator.d
@@ -103,10 +103,6 @@ struct Mallocator
     test!Mallocator();
 }
 
-version (Posix)
-@nogc nothrow
-private extern(C) int posix_memalign(void**, size_t, size_t);
-
 version (Windows)
 {
     // DMD Win 32 bit, DigitalMars C standard library misses the _aligned_xxx
@@ -229,6 +225,7 @@ struct AlignedMallocator
     void[] alignedAllocate(size_t bytes, uint a) shared
     {
         import core.stdc.errno : ENOMEM, EINVAL;
+        import core.sys.posix.stdlib : posix_memalign;
         assert(a.isGoodDynamicAlignment);
         void* result;
         auto code = posix_memalign(&result, a, bytes);
diff --git a/std/file.d b/std/file.d
index fc0f15b6f70..e8e434c06ca 100644
--- a/std/file.d
+++ b/std/file.d
@@ -4353,11 +4353,6 @@ string tempDir() @trusted
             DWORD len = GetTempPathW(buf.length, buf.ptr);
             if (len) cache = buf[0 .. len].to!string;
         }
-        else version(Android)
-        {
-            // Don't check for a global temporary directory as
-            // Android doesn't have one.
-        }
         else version(Posix)
         {
             import std.process : environment;
diff --git a/std/math.d b/std/math.d
index b029c50d375..8db6acbb906 100644
--- a/std/math.d
+++ b/std/math.d
@@ -4816,7 +4816,7 @@ public:
     assert(ieeeFlags == f);
 }
 
-@system unittest
+version(D_HardFloat) @system unittest
 {
     import std.meta : AliasSeq;
 
@@ -5260,7 +5260,7 @@ private:
     ensureDefaults();
 }
 
-@system unittest // rounding
+version(D_HardFloat) @system unittest // rounding
 {
     import std.meta : AliasSeq;
 
diff --git a/std/system.d b/std/system.d
index dbc0f846986..2320ff09b20 100644
--- a/std/system.d
+++ b/std/system.d
@@ -28,7 +28,7 @@ immutable
     {
         win32 = 1, /// Microsoft 32 bit Windows systems
         win64,     /// Microsoft 64 bit Windows systems
-        linux,     /// All Linux Systems
+        linux,     /// All Linux Systems, except for Android
         osx,       /// Mac OS X
         freeBSD,   /// FreeBSD
         netBSD,    /// NetBSD