diff --git a/NEWS.md b/NEWS.md
index 23e16de..b69c791 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -4,6 +4,11 @@
 
 ## Bug fixes
 
+- Fixed a bug in which `cost_to_closest()` would return `NA` values when
+  filling missing ids (which should be filled with `Inf`, since they cannot
+  reach any opportunities). This was also responsible for the warning reported
+  in #27, which was also fixed.
+
 ## Notes
 
 # accessibility 1.0.0
diff --git a/R/cost_to_closest.R b/R/cost_to_closest.R
index ff19b2f..c5548de 100644
--- a/R/cost_to_closest.R
+++ b/R/cost_to_closest.R
@@ -115,6 +115,8 @@ cost_to_closest <- function(travel_matrix,
     possible_combinations <- do.call(data.table::CJ, unique_values)
 
     if (nrow(access) < nrow(possible_combinations)) {
+      access[, min_cost := as.numeric(min_cost)]
+
       access <- do_fill_missing_ids(
         access,
         possible_combinations,