diff --git a/src/core/Date.pm6 b/src/core/Date.pm6
index da2a8c0f428..a68161435e4 100644
--- a/src/core/Date.pm6
+++ b/src/core/Date.pm6
@@ -21,9 +21,15 @@ my class Date does Dateish {
           !! X::DateTime::InvalidDeltaUnit.new(:$unit).throw
     }
 
-    method !SET-SELF(
-      $!year,$!month,$!day,&!formatter,$!daycount = Int
-    --> Date:D) { self }
+    method !SET-SELF(\year,\month,\day,\formatter,$daycount? --> Date:D) {
+        nqp::bind($!year,      year);  # R#2581
+        nqp::bind($!month,     month);
+        nqp::bind($!day,       day);
+        nqp::bind(&!formatter, formatter);
+        nqp::bind($!daycount,
+          nqp::isconcrete($daycount) ?? $daycount !! nqp::null);
+        self
+    }
 
     proto method new(|) {*}
     multi method new(Date:
diff --git a/src/core/DateTime.pm6 b/src/core/DateTime.pm6
index 605fd7b30bc..7a114dde7dc 100644
--- a/src/core/DateTime.pm6
+++ b/src/core/DateTime.pm6
@@ -1,8 +1,8 @@
 my class DateTime does Dateish {
-    has int $.hour;
-    has int $.minute;
+    has Int $.hour;
+    has Int $.minute;
     has     $.second;
-    has int $.timezone;  # UTC
+    has Int $.timezone;  # UTC
       # Not an optimization but a necessity to ensure that
       # $dt.utc.local.utc is equivalent to $dt.utc. Otherwise,
       # DST-induced ambiguity could ruin our day.
@@ -48,17 +48,27 @@ my class DateTime does Dateish {
     }
 
     method !SET-SELF(
-        $!year,
-        $!month,
-        $!day,
-        $!hour,
-        $!minute,
-        $!second,
-        $!timezone,
-        &!formatter,
+        Int:D \year,
+        Int:D \month,
+        Int:D \day,
+        Int:D \hour,
+        Int:D \minute,
+              \second,
+        Int:D \timezone,
+              &formatter
     --> DateTime:D) {
+        nqp::bind($!year,      year);  # R#2581
+        nqp::bind($!month,     month);
+        nqp::bind($!day,       day);
+        nqp::bind(&!formatter, &formatter);
+        nqp::bind($!daycount,  nqp::null);
+        $!hour      := hour;
+        $!minute    := minute;
+        $!second    := second;
+        $!timezone  := timezone;
         self
     }
+
     method !new-from-positional(DateTime:
       Int() $year,
       Int() $month,
diff --git a/src/core/Dateish.pm6 b/src/core/Dateish.pm6
index ab2562af9ef..1d3fac4c8df 100644
--- a/src/core/Dateish.pm6
+++ b/src/core/Dateish.pm6
@@ -1,7 +1,7 @@
 my role Dateish {
     has Int $.year;
-    has Int $.month;     # should be int
-    has Int $.day;       # should be int
+    has Int $.month;
+    has Int $.day;
     has Int $.daycount;
     has     &.formatter;
 
@@ -44,14 +44,19 @@ my role Dateish {
     multi method gist(Dateish:D: --> Str:D) { self.Str }
 
     method daycount(--> Int:D) {
-        $!daycount //= do {
-            # taken from <http://www.merlyn.demon.co.uk/daycount.htm>
-            my int $m = $!month < 3 ?? $!month + 12 !! $!month;
-            my int $y = $!year - ($!month < 3);
-            -678973 + $!day + (153 * $m - 2) div 5
-              + 365 * $y + $y div 4
-              - $y div 100  + $y div 400;
-        }
+        nqp::ifnull(
+          $!daycount,
+          $!daycount := self!calculate-daycount
+        )
+    }
+    method !calculate-daycount(--> Int:D) {
+        # taken from <http://www.merlyn.demon.co.uk/daycount.htm>
+        my int $d = $!day;
+        my int $m = $!month < 3 ?? $!month + 12 !! $!month;
+        my int $y = $!year - ($!month < 3);
+        -678973 + $d + (153 * $m - 2) div 5
+          + 365 * $y + $y div 4
+          - $y div 100  + $y div 400
     }
 
     method !ymd-from-daycount($daycount,\year,\month,\day --> Nil) {