diff --git a/std/experimental/allocator/building_blocks/kernighan_ritchie.d b/std/experimental/allocator/building_blocks/kernighan_ritchie.d
index 328497f44d3..77c8e31e8f7 100644
--- a/std/experimental/allocator/building_blocks/kernighan_ritchie.d
+++ b/std/experimental/allocator/building_blocks/kernighan_ritchie.d
@@ -3,8 +3,7 @@
 Source: $(PHOBOSSRC std/experimental/allocator/building_blocks/kernighan_ritchie.d)
 */
 module std.experimental.allocator.building_blocks.kernighan_ritchie;
-import std.experimental.allocator.building_blocks.null_allocator :
-    NullAllocator;
+import std.experimental.allocator.building_blocks.null_allocator;
 
 //debug = KRRegion;
 debug(KRRegion) import std.stdio;
@@ -362,7 +361,7 @@ struct KRRegion(ParentAllocator = NullAllocator)
     /// Ditto
     static if (!is(ParentAllocator == NullAllocator)
         && hasMember!(ParentAllocator, "deallocate"))
-    ~this()
+    @trusted ~this()
     {
         parent.deallocate(payload);
     }
@@ -652,7 +651,7 @@ fronting the GC allocator.
     import std.experimental.allocator.gc_allocator : GCAllocator;
     import std.typecons : Ternary;
     // KRRegion fronting a general-purpose allocator
-    align(KRRegion!().alignment) ubyte[1024 * 128] buf;
+    ubyte[1024 * 128] buf;
     auto alloc = fallbackAllocator(KRRegion!()(buf), GCAllocator.instance);
     auto b = alloc.allocate(100);
     assert(b.length == 100);
@@ -674,6 +673,7 @@ it actually returns memory to the operating system when possible.
     import std.algorithm.comparison : max;
     import std.experimental.allocator.building_blocks.allocator_list
         : AllocatorList;
+    import std.experimental.allocator.gc_allocator : GCAllocator;
     import std.experimental.allocator.mmap_allocator : MmapAllocator;
     AllocatorList!(n => KRRegion!MmapAllocator(max(n * 16, 1024 * 1024))) alloc;
 }
@@ -683,6 +683,7 @@ it actually returns memory to the operating system when possible.
     import std.algorithm.comparison : max;
     import std.experimental.allocator.building_blocks.allocator_list
         : AllocatorList;
+    import std.experimental.allocator.gc_allocator : GCAllocator;
     import std.experimental.allocator.mallocator : Mallocator;
     import std.typecons : Ternary;
     /*
@@ -715,6 +716,7 @@ it actually returns memory to the operating system when possible.
     import std.algorithm.comparison : max;
     import std.experimental.allocator.building_blocks.allocator_list
         : AllocatorList;
+    import std.experimental.allocator.gc_allocator : GCAllocator;
     import std.experimental.allocator.mmap_allocator : MmapAllocator;
     import std.typecons : Ternary;
     /*
@@ -747,7 +749,6 @@ it actually returns memory to the operating system when possible.
     }
 }
 
-version (StdUnittest)
 @system unittest
 {
     import std.algorithm.comparison : max;
@@ -759,12 +760,13 @@ version (StdUnittest)
         n => KRRegion!GCAllocator(max(n * 16, 1024 * 1024)))());
 }
 
-@safe unittest
+@trusted unittest
 {
     import std.experimental.allocator.gc_allocator : GCAllocator;
-
     auto alloc = KRRegion!GCAllocator(1024 * 1024);
 
+
+
     void[][] array;
     foreach (i; 1 .. 4)
     {
@@ -785,9 +787,9 @@ version (StdUnittest)
                     cast(ubyte[])(GCAllocator.instance.allocate(1024 * 1024)));
     const store = (() pure nothrow @safe @nogc => alloc.allocate(KRRegion!().sizeof))();
     auto p = cast(KRRegion!()* ) store.ptr;
-    import core.lifetime : emplace;
     import core.stdc.string : memcpy;
-    import std.conv : text;
+    import std.algorithm.mutation : move;
+    import std.conv : text, emplace;
 
     memcpy(p, &alloc, alloc.sizeof);
     emplace(&alloc);
@@ -825,14 +827,16 @@ version (StdUnittest)
     assert(p.length == 1024 * 1024);
 }
 
+
 @safe unittest
 {
-    import std.random : randomCover;
+    import std.experimental.allocator.building_blocks;
+    import std.random;
     import std.typecons : Ternary;
 
     // Both sequences must work on either system
 
-    // A sequence of allocs which generates the error described in https://issues.dlang.org/show_bug.cgi?id=16564
+    // A sequence of allocs which generates the error described in issue 16564
     // that is a gap at the end of buf from the perspective of the allocator
 
     // for 64 bit systems (leftover balance = 8 bytes < 16)
@@ -842,10 +846,10 @@ version (StdUnittest)
     int[] sizes32 = [81412, 107068, 49892, 23768];
 
 
-    void test(int[] sizes)
+    @system void test(int[] sizes)
     {
         align(size_t.sizeof) ubyte[256 * 1024] buf;
-        auto a = KRRegion!()(buf);
+        auto a = (() @trusted => createAllocator(buf))();
 
         void[][] bufs;
 
@@ -862,12 +866,22 @@ version (StdUnittest)
         assert((() pure nothrow @safe @nogc => a.empty)() == Ternary.yes);
     }
 
-    test(sizes64);
-    test(sizes32);
+    () @trusted {
+        test(sizes64);
+        test(sizes32);
+    }();
 }
 
+@safe KRRegion!NullAllocator createAllocator(ubyte[] buf)
+{
+    return KRRegion!NullAllocator(buf);
+}
+
+
 @safe unittest
 {
+    import std.experimental.allocator.building_blocks;
+    import std.random;
     import std.typecons : Ternary;
 
     // For 64 bits, we allocate in multiples of 8, but the minimum alloc size is 16.
@@ -921,7 +935,7 @@ version (StdUnittest)
 @system unittest
 {   import std.typecons : Ternary;
 
-    align(KRRegion!().alignment) ubyte[1024] b;
+    ubyte[1024] b;
     auto alloc = KRRegion!()(b);
 
     auto k = alloc.allocate(128);
@@ -941,4 +955,4 @@ version (StdUnittest)
     assert(alloc.empty == Ternary.no);
     assert(alloc.deallocate(k));
     assert(alloc.empty == Ternary.yes);
-}
+}
\ No newline at end of file