diff --git a/DESCRIPTION b/DESCRIPTION
index 235db095aa05e28511ca813b881ee8fb3a074b7e..553a7042d41dd4d5806b2beccbd9fabe93f3388a 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,7 +1,7 @@
 Package: onlineforecast
 Type: Package
 Title: Forecast Modelling for Online Applications
-Version: 0.10.0
+Version: 0.10.1
 Description: A framework for fitting adaptive forecasting models. Provides a way to use forecasts as input to models, e.g. weather forecasts for energy related forecasting. The models can be fitted recursively and can easily be setup for updating parameters when new data arrives. See the included vignettes, the website <https://onlineforecasting.org> and the paper "Short-term heat load forecasting for single family houses" <doi:10.1016/j.enbuild.2013.04.022>.
 License: GPL-3
 Encoding: UTF-8
diff --git a/R/forecastmodel.R b/R/forecastmodel.R
index 2c0c5954a93987b517ca6cf2102327b5fcf8fdcc..1de0860a1e9aed3662ab4556a1fdd52f47e86635 100644
--- a/R/forecastmodel.R
+++ b/R/forecastmodel.R
@@ -292,7 +292,9 @@ forecastmodel <- R6::R6Class("forecastmodel", public = list(
                         stop("The input variable '",nm,"' doesn't have the same number of observations as time vector 't' in the data. It has ",length(data[[nm]]),", but 't' has ",length(data$t))
                     }
                 }else{
-                    stop("The variable '",nm,"' is missing in data, or it has the wrong class.\nIt must be class: data.frame, matrix or vector.\nIt is needed for the input expression '",self$inputs[[i]]$expr[[1]],"'")
+                    if(!nm == "pi"){
+                        stop("The variable '",nm,"' is missing in data, or it has the wrong class.\nIt must be class: data.frame, matrix or vector.\nIt is needed for the input expression '",self$inputs[[i]]$expr[[1]],"'")
+                    }
                 }
             }
         }