diff --git a/ChangeLog b/ChangeLog
index 5a614f467b..f33887c12e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Sep 24 10:06:19 2009  Marc-Andre Lafortune  <ruby-core@marc-andre.ca>
+
+	* lib/mathn.rb (Fixnum#**, Float#**, Bignum#**): Allow fractional
+	  power for negative numbers when 'mathn' is required [redmine:783]
+
 Wed Sep 23 05:36:55 2009  Marc-Andre Lafortune  <ruby-core@marc-andre.ca>
 
 	* eval.c (umethod_bind): Fix bug that disallowed methods from
diff --git a/lib/mathn.rb b/lib/mathn.rb
index 482a4f366a..7d16923670 100644
--- a/lib/mathn.rb
+++ b/lib/mathn.rb
@@ -108,10 +108,30 @@ end
 
 class Fixnum
   alias / quo
+
+  alias power! ** unless method_defined? :power!
+
+  def ** (other)
+    if self < 0 && other.round != other
+      Complex.new(self, 0.0) ** other
+    else
+      power!(other)
+    end
+  end
 end
 
 class Bignum
   alias / quo
+
+  alias power! ** unless method_defined? :power!
+
+  def ** (other)
+    if self < 0 && other.round != other
+      Complex.new(self, 0.0) ** other
+    else
+      power!(other)
+    end
+  end
 end
 
 class Rational
@@ -306,3 +326,15 @@ class Complex
   Unify = true
 end
 
+class Float
+  alias power! **
+
+  def ** (other)
+    if self < 0 && other.round != other
+      Complex.new(self, 0.0) ** other
+    else
+      power!(other)
+    end
+  end
+
+end