diff --git a/ApplicationCode/ProjectDataModel/RimLegendConfig.cpp b/ApplicationCode/ProjectDataModel/RimLegendConfig.cpp
index 903688845d..477b22e887 100644
--- a/ApplicationCode/ProjectDataModel/RimLegendConfig.cpp
+++ b/ApplicationCode/ProjectDataModel/RimLegendConfig.cpp
@@ -639,7 +639,7 @@ void RimLegendConfig::setCategoryColors(const std::vector<cvf::Color3ub>& catego
 //--------------------------------------------------------------------------------------------------
 /// 
 //--------------------------------------------------------------------------------------------------
-QString RimLegendConfig::categoryNameFromCategoryValue(size_t categoryValue) const
+QString RimLegendConfig::categoryNameFromCategoryValue(int categoryValue) const
 {
     if (m_categoryNames.size() > 0)
     {
diff --git a/ApplicationCode/ProjectDataModel/RimLegendConfig.h b/ApplicationCode/ProjectDataModel/RimLegendConfig.h
index 76544dedf0..013d3b7b8e 100644
--- a/ApplicationCode/ProjectDataModel/RimLegendConfig.h
+++ b/ApplicationCode/ProjectDataModel/RimLegendConfig.h
@@ -110,7 +110,7 @@ public:
     void                                        setNamedCategoriesInverse(const std::vector<QString>& categoryNames);
     void                                        setNamedCategories(const std::vector<QString>& categoryNames);
     void                                        setCategoryColors(const std::vector<cvf::Color3ub>& categoryColors);
-    QString                                     categoryNameFromCategoryValue(size_t categoryValue) const;
+    QString                                     categoryNameFromCategoryValue(int categoryValue) const;
 
     void                                        setTitle(const cvf::String& title);