diff --git a/R/engine_bart.R b/R/engine_bart.R
index e8b7130a..fb81a162 100644
--- a/R/engine_bart.R
+++ b/R/engine_bart.R
@@ -319,7 +319,8 @@ engine_bart <- function(x,
 
         # All other needed data for model fitting
         equation <- model$biodiversity[[1]]$equation
-        data <- cbind(model$biodiversity[[1]]$predictors, data.frame(observed = model$biodiversity[[1]]$observations[,'observed']) )
+        data <- cbind(model$biodiversity[[1]]$predictors,
+                      data.frame(observed = model$biodiversity[[1]]$observations[,'observed', drop = TRUE]) )
         # Subset to predictor names
         data <- subset(data, select = c('observed', model$biodiversity[[1]]$predictors_names) )
         if(model$biodiversity[[1]]$family=='binomial') data$observed <- factor(data$observed)
diff --git a/R/engine_breg.R b/R/engine_breg.R
index 833d8cdb..75de1449 100644
--- a/R/engine_breg.R
+++ b/R/engine_breg.R
@@ -321,7 +321,7 @@ engine_breg <- function(x,
         if(!is.null(li)) if(getOption('ibis.setupmessages')) myLog('[Estimation]','red',paste0("Package does not support custom link functions. Ignored!"))
         form <- model$biodiversity[[1]]$equation
         df <- cbind(model$biodiversity[[1]]$predictors,
-                    data.frame(observed = model$biodiversity[[1]]$observations[,'observed'])
+                    data.frame(observed = model$biodiversity[[1]]$observations[,'observed', drop = TRUE])
                     )
         df <- subset(df, select = c(model$biodiversity[[1]]$predictors_names, "observed"))
         w <- model$biodiversity[[1]]$expect # The expected exposure
diff --git a/R/engine_gdb.R b/R/engine_gdb.R
index 360e69d0..d769d541 100644
--- a/R/engine_gdb.R
+++ b/R/engine_gdb.R
@@ -324,7 +324,8 @@ engine_gdb <- function(x,
 
         # All other needed data for model fitting
         equation <- model$biodiversity[[1]]$equation
-        data <- cbind(model$biodiversity[[1]]$predictors, data.frame(observed = model$biodiversity[[1]]$observations[,'observed']) )
+        data <- cbind(model$biodiversity[[1]]$predictors,
+                      data.frame(observed = model$biodiversity[[1]]$observations[,'observed', drop = TRUE]) )
         w <- model$biodiversity[[1]]$expect
 
         # Select predictors
diff --git a/R/engine_glmnet.R b/R/engine_glmnet.R
index f6ca2867..745e16ad 100644
--- a/R/engine_glmnet.R
+++ b/R/engine_glmnet.R
@@ -321,7 +321,7 @@ engine_glmnet <- function(x,
 
         form <- model$biodiversity[[1]]$equation
         df <- cbind(model$biodiversity[[1]]$predictors,
-                    data.frame(observed = model$biodiversity[[1]]$observations[,'observed'])
+                    data.frame(observed = model$biodiversity[[1]]$observations[,'observed', drop = TRUE])
         )
         df <- subset(df, select = c(model$biodiversity[[1]]$predictors_names, "observed"))
         w <- df$w <- model$biodiversity[[1]]$expect # The expected exposure