diff --git a/std/experimental/allocator/package.d b/std/experimental/allocator/package.d
index 323aa4dfa..ac113cf60 100644
--- a/std/experimental/allocator/package.d
+++ b/std/experimental/allocator/package.d
@@ -895,7 +895,17 @@ nothrow @safe @nogc unittest
     assertThrown(make!InvalidImpureStruct(Mallocator.instance, 42));
 }
 
-private void fillWithMemcpy(T)(void[] array, auto ref T filler) nothrow
+private void fillWithMemcpy(T)(scope void[] array, auto ref T filler) nothrow
+if (T.sizeof == 1)
+{
+    import core.stdc.string : memset;
+    import std.traits : CopyConstness;
+    if (!array.length) return;
+    memset(array.ptr, *cast(CopyConstness!(T*, ubyte*)) &filler, array.length);
+}
+
+private void fillWithMemcpy(T)(scope void[] array, auto ref T filler) nothrow
+if (T.sizeof != 1)
 {
     import core.stdc.string : memcpy;
     import std.algorithm.comparison : min;
@@ -910,6 +920,17 @@ private void fillWithMemcpy(T)(void[] array, auto ref T filler) nothrow
     }
 }
 
+@system unittest
+{
+    // Test T.sizeof == 1 path of fillWithMemcpy.
+    ubyte[] a;
+    fillWithMemcpy(a, ubyte(42));
+    assert(a.length == 0);
+    a = [ 1, 2, 3, 4, 5 ];
+    fillWithMemcpy(a, ubyte(42));
+    assert(a == [ 42, 42, 42, 42, 42]);
+}
+
 @system unittest
 {
     int[] a;