diff --git a/R/plotSequenceRatios.R b/R/plotSequenceRatios.R
index e16ea25..ba952ba 100644
--- a/R/plotSequenceRatios.R
+++ b/R/plotSequenceRatios.R
@@ -35,6 +35,9 @@ plotSequenceRatios <- function(result,
                                colours = c("red", "blue"),
                                facet = NULL
                                ){
+
+  rlang::check_installed("ggplot2")
+
   # validate checks
   result <- omopgenerics::validateResultArgument(result)
 
diff --git a/R/plotTemporalSymmetry.R b/R/plotTemporalSymmetry.R
index 312ca08..ae0d595 100644
--- a/R/plotTemporalSymmetry.R
+++ b/R/plotTemporalSymmetry.R
@@ -35,6 +35,9 @@ plotTemporalSymmetry <- function(result,
                                  xlim = c(-12, 12),
                                  colours = c("blue", "red"),
                                  scales = "free") {
+
+  rlang::check_installed("ggplot2")
+
   # checks
   checkInputPlotTemporalSymmetry(result = result,
                                  plotTitle = plotTitle,