diff --git a/R/pkg/R/mllib.R b/R/pkg/R/mllib.R
index 25d9f077b487c054f58f994607c57ed7de42b724..6f6e2fc255c3fd8a9a820707e5c8bcc8e08d0261 100644
--- a/R/pkg/R/mllib.R
+++ b/R/pkg/R/mllib.R
@@ -140,7 +140,7 @@ setMethod("spark.glm", signature(data = "SparkDataFrame", formula = "formula"),
 
             jobj <- callJStatic("org.apache.spark.ml.r.GeneralizedLinearRegressionWrapper",
                                 "fit", formula, data@sdf, family$family, family$link,
-                                tol, as.integer(maxIter), weightCol)
+                                tol, as.integer(maxIter), as.character(weightCol))
             return(new("GeneralizedLinearRegressionModel", jobj = jobj))
           })