diff --git a/src/core/demangle.d b/src/core/demangle.d
index f5c412a41e..451292eddd 100644
--- a/src/core/demangle.d
+++ b/src/core/demangle.d
@@ -2416,7 +2416,7 @@ else version (Darwin)
 else
     enum string cPrefix = "";
 
-version (unittest)
+@safe pure nothrow unittest
 {
     immutable string[2][] table =
     [
@@ -2544,9 +2544,6 @@ version (unittest)
         else
             alias staticIota = Seq!(staticIota!(x - 1), x - 1);
     }
-}
-@safe pure nothrow unittest
-{
     foreach ( i, name; table )
     {
         auto r = demangle( name[0] );
diff --git a/src/core/internal/convert.d b/src/core/internal/convert.d
index 9a3889079c..7bbef4daff 100644
--- a/src/core/internal/convert.d
+++ b/src/core/internal/convert.d
@@ -465,14 +465,14 @@ private Float denormalizedMantissa(T)(T x, uint sign) if (floatFormat!T == Float
         return Float(fl.mantissa2 & 0x00FFFFFFFFFFFFFFUL , 0, sign, 1);
 }
 
-version (unittest)
+@system unittest
 {
-    private const(ubyte)[] toUbyte2(T)(T val)
+    static const(ubyte)[] toUbyte2(T)(T val)
     {
         return toUbyte(val).dup;
     }
 
-    private void testNumberConvert(string v)()
+    static void testNumberConvert(string v)()
     {
         enum ctval = mixin(v);
 
@@ -488,7 +488,7 @@ version (unittest)
         assert(rtbytes[0..testsize] == ctbytes[0..testsize]);
     }
 
-    private void testConvert()
+    static void testConvert()
     {
         /**Test special values*/
         testNumberConvert!("-float.infinity");
@@ -598,11 +598,7 @@ version (unittest)
         testNumberConvert!("cast(float)0x9.54bb0d88806f714p-7088L");
     }
 
-
-    unittest
-    {
-        testConvert();
-    }
+    testConvert();
 }
 
 
diff --git a/src/core/lifetime.d b/src/core/lifetime.d
index 93b562cd73..ece88b9d54 100644
--- a/src/core/lifetime.d
+++ b/src/core/lifetime.d
@@ -239,6 +239,21 @@ T emplace(T, Args...)(void[] chunk, auto ref Args args)
 
 @nogc pure nothrow @safe unittest
 {
+    static class __conv_EmplaceTestClass
+    {
+        int i = 3;
+        this(int i) @nogc @safe pure nothrow
+        {
+            assert(this.i == 3 && i == 5);
+            this.i = i;
+        }
+        this(int i, ref int j) @nogc @safe pure nothrow
+        {
+            assert(i == 5 && j == 6);
+            this.i = i;
+            ++j;
+        }
+    }
     int var = 6;
     align(__conv_EmplaceTestClass.alignof) ubyte[__traits(classInstanceSize, __conv_EmplaceTestClass)] buf;
     auto support = (() @trusted => cast(__conv_EmplaceTestClass)(buf.ptr))();
@@ -306,43 +321,6 @@ T* emplace(T, Args...)(void[] chunk, auto ref Args args)
     assert(u1.a == "hello");
 }
 
-version (unittest) private struct __conv_EmplaceTest
-{
-    int i = 3;
-    this(int i)
-    {
-        assert(this.i == 3 && i == 5);
-        this.i = i;
-    }
-    this(int i, ref int j)
-    {
-        assert(i == 5 && j == 6);
-        this.i = i;
-        ++j;
-    }
-
-@disable:
-    this();
-    this(this);
-    void opAssign();
-}
-
-version (unittest) private class __conv_EmplaceTestClass
-{
-    int i = 3;
-    this(int i) @nogc @safe pure nothrow
-    {
-        assert(this.i == 3 && i == 5);
-        this.i = i;
-    }
-    this(int i, ref int j) @nogc @safe pure nothrow
-    {
-        assert(i == 5 && j == 6);
-        this.i = i;
-        ++j;
-    }
-}
-
 @system unittest // bugzilla 15772
 {
     abstract class Foo {}
@@ -476,17 +454,40 @@ version (unittest) private class __conv_EmplaceTestClass
 
 @system unittest
 {
+    static struct __conv_EmplaceTest
+    {
+        int i = 3;
+        this(int i)
+        {
+            assert(this.i == 3 && i == 5);
+            this.i = i;
+        }
+        this(int i, ref int j)
+        {
+            assert(i == 5 && j == 6);
+            this.i = i;
+            ++j;
+        }
+
+    @disable:
+        this();
+        this(this);
+        void opAssign();
+    }
+
     __conv_EmplaceTest k = void;
     emplace(&k, 5);
     assert(k.i == 5);
-}
 
-@system unittest
-{
     int var = 6;
-    __conv_EmplaceTest k = void;
-    emplace(&k, 5, var);
-    assert(k.i == 5);
+    __conv_EmplaceTest x = void;
+    emplace(&x, 5, var);
+    assert(x.i == 5);
+    assert(var == 7);
+
+    var = 6;
+    auto z = emplace!__conv_EmplaceTest(new void[__conv_EmplaceTest.sizeof], 5, var);
+    assert(z.i == 5);
     assert(var == 7);
 }
 
@@ -1162,14 +1163,6 @@ pure nothrow @safe /* @nogc */ unittest
     assert(n.refs == 10);
 }
 
-@system unittest
-{
-    int var = 6;
-    auto k = emplace!__conv_EmplaceTest(new void[__conv_EmplaceTest.sizeof], 5, var);
-    assert(k.i == 5);
-    assert(var == 7);
-}
-
 @system unittest
 {
     class A