diff --git a/std/file.d b/std/file.d
index ae1568681..a110bdb51 100644
--- a/std/file.d
+++ b/std/file.d
@@ -629,7 +629,7 @@ if (isSomeString!S && (isInputRange!R && !isInfinite!R && isSomeChar!(ElementTyp
     static assert(__traits(compiles, readText(TestAliasedString(null))));
 }
 
-@system unittest
+@safe unittest
 {
     import std.array : appender;
     import std.bitmanip : append, Endian;
@@ -748,7 +748,7 @@ if ((isInputRange!R && !isInfinite!R && isSomeChar!(ElementEncodingType!R) || is
 }
 
 ///
-@system unittest
+@safe unittest
 {
    scope(exit)
    {
@@ -758,7 +758,9 @@ if ((isInputRange!R && !isInfinite!R && isSomeChar!(ElementEncodingType!R) || is
 
    int[] a = [ 0, 1, 1, 2, 3, 5, 8 ];
    write(deleteme, a); // deleteme is the name of a temporary file
-   assert(cast(int[]) read(deleteme) == a);
+   const bytes = read(deleteme);
+   const fileInts = () @trusted { return cast(int[]) bytes; }();
+   assert(fileInts == a);
 }
 
 /// ditto
@@ -795,7 +797,7 @@ if ((isInputRange!R && !isInfinite!R && isSomeChar!(ElementEncodingType!R) || is
 }
 
 ///
-@system unittest
+@safe unittest
 {
    scope(exit)
    {
@@ -807,7 +809,9 @@ if ((isInputRange!R && !isInfinite!R && isSomeChar!(ElementEncodingType!R) || is
    write(deleteme, a); // deleteme is the name of a temporary file
    int[] b = [ 13, 21 ];
    append(deleteme, b);
-   assert(cast(int[]) read(deleteme) == a ~ b);
+   const bytes = read(deleteme);
+   const fileInts = () @trusted { return cast(int[]) bytes; }();
+   assert(fileInts == a ~ b);
 }
 
 /// ditto
@@ -1303,7 +1307,7 @@ if (isConvertibleToString!R)
     static assert(__traits(compiles, getTimes(TestAliasedString("foo"), atime, mtime)));
 }
 
-@system unittest
+@safe unittest
 {
     import std.stdio : writefln;
 
@@ -1312,8 +1316,8 @@ if (isConvertibleToString!R)
     write(deleteme, "a");
     scope(exit) assert(deleteme.exists), deleteme.remove;
 
-    SysTime accessTime1 = void;
-    SysTime modificationTime1 = void;
+    SysTime accessTime1;
+    SysTime modificationTime1;
 
     getTimes(deleteme, accessTime1, modificationTime1);
 
@@ -1616,7 +1620,7 @@ private void setTimesImpl(scope const(char)[] names, scope const(FSChar)* namez,
         setTimes(TestAliasedString("foo"), SysTime.init, SysTime.init);
 }
 
-@system unittest
+@safe unittest
 {
     import std.stdio : File;
     string newdir = deleteme ~ r".dir";
@@ -1885,7 +1889,7 @@ else version (Posix)
 version (FreeBSD) {} else
 version (DragonFlyBSD) {} else
 version (OSX) {} else
-@system unittest
+@safe unittest
 {
     import core.thread;
 
@@ -1900,7 +1904,7 @@ version (OSX) {} else
         remove(deleteme);
         assert(time != lastTime);
         lastTime = time;
-        Thread.sleep(20.msecs);
+        () @trusted { Thread.sleep(20.msecs); }();
     }
 }
 
@@ -2403,7 +2407,7 @@ if (isConvertibleToString!R)
     }
 }
 
-@system unittest
+@safe unittest
 {
     version (Windows)
         enum dir = "C:\\Program Files\\";
@@ -2554,7 +2558,7 @@ if (isConvertibleToString!R)
 }
 
 // https://issues.dlang.org/show_bug.cgi?id=15658
-@system unittest
+@safe unittest
 {
     DirEntry e = DirEntry(".");
     static assert(is(typeof(isFile(e))));
@@ -3063,7 +3067,7 @@ void mkdirRecurse(scope const(char)[] pathname) @safe
 }
 
 ///
-@system unittest
+@safe unittest
 {
     import std.path : buildPath;
 
@@ -3188,7 +3192,7 @@ if (isConvertibleToString!R)
 }
 
 ///
-@system unittest
+@safe unittest
 {
     auto dir = deleteme ~ "dir";