diff --git a/packages/random/mt.pony b/packages/random/mt.pony
index 4b969c0f5c..acf75fa4b6 100644
--- a/packages/random/mt.pony
+++ b/packages/random/mt.pony
@@ -28,7 +28,7 @@ class MT is Random
 
   fun ref next(): U64 =>
     """
-    A random integer in [0, 2^64 - 1]
+    A random integer in [0, 2^64)
     """
     if _index >= _n() then
       _populate()
diff --git a/packages/random/xoroshiro.pony b/packages/random/xoroshiro.pony
index 612313886d..cd950093b0 100644
--- a/packages/random/xoroshiro.pony
+++ b/packages/random/xoroshiro.pony
@@ -16,10 +16,11 @@ class XorOshiro128Plus is Random
     """
     _x = x
     _y = y
+    next()
 
   fun ref next(): U64 =>
     """
-    A random integer in [0, 2^64 - 1]
+    A random integer in [0, 2^64)
     """
     let x = _x
     var y = _y
diff --git a/packages/random/xorshift.pony b/packages/random/xorshift.pony
index bc1c5bb8fb..08849258a3 100644
--- a/packages/random/xorshift.pony
+++ b/packages/random/xorshift.pony
@@ -17,10 +17,11 @@ class XorShift128Plus is Random
     """
     _x = x
     _y = y
+    next()
 
   fun ref next(): U64 =>
     """
-    A random integer in [0, 2^64 - 1]
+    A random integer in [0, 2^64)
     """
     var y = _x
     let x = _y