diff --git a/bitwise.hpp b/bitwise.hpp
index d3b5f016..ec31a78e 100644
--- a/bitwise.hpp
+++ b/bitwise.hpp
@@ -67,19 +67,29 @@ namespace cruft {
 
 
     ///////////////////////////////////////////////////////////////////////////
-    template <
-        typename T,
-        typename = std::enable_if_t<
-            std::is_integral_v<T>
-        >
-    >
-    constexpr T
-    popcount (T t)
+    constexpr unsigned
+    popcount (unsigned t)
     {
         return __builtin_popcount (t);
     }
 
 
+    //-------------------------------------------------------------------------
+    constexpr unsigned long
+    popcount (unsigned long t)
+    {
+        return __builtin_popcountl (t);
+    }
+
+
+    //-------------------------------------------------------------------------
+    constexpr unsigned long long
+    popcount (unsigned long long t)
+    {
+        return __builtin_popcountll (t);
+    }
+
+
     ///////////////////////////////////////////////////////////////////////////
     /// returns the integral value composed of the bits from `val' in the
     /// inclusive range [lo, hi].