diff --git a/R/biproportional.R b/R/biproportional.R
index 066d956..eeb4712 100644
--- a/R/biproportional.R
+++ b/R/biproportional.R
@@ -434,7 +434,7 @@ lower_apportionment = function(votes_matrix, seats_cols,
     }
 
     # create output
-    output = round(m.(M, dD, dP))
+    output = round_func(m.(M, dD, dP))
     dimnames(output) <- dimnames(M)
     attributes(output)$divisors <- list()
     attributes(output)$divisors$districts <- dD
diff --git a/tests/testthat/test-biproportional.R b/tests/testthat/test-biproportional.R
index ed8b7cf..a5e7288 100644
--- a/tests/testthat/test-biproportional.R
+++ b/tests/testthat/test-biproportional.R
@@ -32,6 +32,11 @@ test_that("lower apportionment", {
         lower_apportionment(matrix(c(1,0,1,0), 2), c(1,1), c(2,0), method = "harmonic"),
         'Lower apportionment is only guaranteed to terminate with the default Sainte-Lagu\u00EB/Webster method (method = "round")',
         fixed = TRUE)
+
+    # exact 0.5 seats edge case
+    vm0.5 = matrix(c(10, 10, 20, 10), 2, 2)
+    sm0.5 = lower_apportionment(vm0.5, c(1, 1), c(1,1))
+    expect_equal(sum(sm0.5), 2)
 })
 
 test_that("biproporz", {