diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 0f24ab4f6e7..3ebfd13bac3 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,9 @@
+2010-06-08  Johannes Singler  <singler@kit.edu>
+
+        * include/parallel/partial_sum.h
+        (__parallel_partial_sum_linear):
+        Correctly calculate part lengths for partial_sum_dilation!=1.
+
 2010-06-07  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR libstdc++/44417
diff --git a/libstdc++-v3/include/parallel/partial_sum.h b/libstdc++-v3/include/parallel/partial_sum.h
index 966d9db0572..d398c4585a2 100644
--- a/libstdc++-v3/include/parallel/partial_sum.h
+++ b/libstdc++-v3/include/parallel/partial_sum.h
@@ -127,10 +127,13 @@ namespace __gnu_parallel
 	    equally_split(__n, __num_threads + 1, __borders);
 	  else
 	    {
+	      _DifferenceType __first_part_length =
+		  std::max<_DifferenceType>(1,
+		    __n / (1.0f + __s.partial_sum_dilation * __num_threads));
 	      _DifferenceType __chunk_length =
-		((double)__n
-		 / ((double)__num_threads + __s.partial_sum_dilation)),
-		__borderstart = __n - __num_threads * __chunk_length;
+		  (__n - __first_part_length) / __num_threads;
+	      _DifferenceType __borderstart =
+		  __n - __num_threads * __chunk_length;
 	      __borders[0] = 0;
 	      for (_ThreadIndex __i = 1; __i < (__num_threads + 1); ++__i)
 		{