diff --git a/R/IWScore.R b/R/IWScore.R
index 602a81192..99c2fe1e6 100644
--- a/R/IWScore.R
+++ b/R/IWScore.R
@@ -39,9 +39,9 @@ IWScore <- function (tree, dataset, concavity=4) {
   homoplasies <- steps - minSteps
   
   # TODO remove this paranoid check once 100% happy with minSteps calculation.
-  if (homoplasies < 0) stop("Minimum steps have been miscalculated.
-                            Please report this bug at
-                            https://github.com/ms609/TreeSearch/issues/new")
+  if (any(homoplasies < 0)) stop("Minimum steps have been miscalculated.\n", 
+                            "       Please report this bug at:\n", 
+                            "       https://github.com/ms609/TreeSearch/issues/new")
   fit <- homoplasies / (homoplasies + concavity)
   # Return:
   sum(fit * weight)