diff --git a/src/ert/gui/tools/plot/plot_case_selection_widget.py b/src/ert/gui/tools/plot/plot_case_selection_widget.py
index b08abb7ded5..bee5dd80ad4 100644
--- a/src/ert/gui/tools/plot/plot_case_selection_widget.py
+++ b/src/ert/gui/tools/plot/plot_case_selection_widget.py
@@ -25,6 +25,7 @@ def __init__(self, case_names):
         self.__add_case_button.setToolButtonStyle(Qt.ToolButtonTextBesideIcon)
         self.__add_case_button.setText("Add case to plot")
         self.__add_case_button.setIcon(QIcon("img:add_circle_outlined.svg"))
+        self.__add_case_button.setEnabled(len(self._cases) > 0)
         self.__add_case_button.clicked.connect(self.addCaseSelector)
 
         add_button_layout.addStretch()