diff --git a/qhtcp-workflow/apps/r/calculate_interaction_zscores.R b/qhtcp-workflow/apps/r/calculate_interaction_zscores.R
index a5a783b6..fbdf3f8b 100644
--- a/qhtcp-workflow/apps/r/calculate_interaction_zscores.R
+++ b/qhtcp-workflow/apps/r/calculate_interaction_zscores.R
@@ -382,7 +382,7 @@ calculate_interaction_scores <- function(df, max_conc, variables, group_vars = c
 
 generate_and_save_plots <- function(output_dir, file_name, plot_configs, grid_layout = NULL) {
 
-  message("Generating html and pdf plots for: ", file_name, ".pdf|html")
+  message("Generating html and pdf plots for: ", file_name)
 
   plots <- lapply(plot_configs, function(config) {
     df <- config$df
@@ -554,8 +554,22 @@ generate_interaction_plot_configs <- function(df, variables) {
 
   # Define which annotations to include for each plot
   annotation_labels <- list(
-    ZShift = function(df, var) paste("ZShift =", round(df[[paste0("Z_Shift_", var)]], 2)),
-    lm_ZScore = function(df, var) paste("lm ZScore =", round(df[[paste0("Z_lm_", var)]], 2)),
+    ZShift = function(df, var) {
+      val <- df[[paste0("Z_Shift_", var)]]
+      if (is.numeric(val)) {
+        paste("ZShift =", round(val, 2))
+      } else {
+        paste("ZShift =", val)
+      }
+    },
+    lm_ZScore = function(df, var) {
+      val <- df[[paste0("Z_lm_", var)]]
+      if (is.numeric(val)) {
+        paste("lm ZScore =", round(val, 2))
+      } else {
+        paste("lm ZScore =", val)
+      }
+    },
     NG = function(df, var) paste("NG =", df$NG),
     DB = function(df, var) paste("DB =", df$DB),
     SM = function(df, var) paste("SM =", df$SM)