diff --git a/NEWS.md b/NEWS.md
index c9d8363..e76e9c8 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,6 +1,7 @@
 # pacs 0.5.1.9000
 
 * update the tinyverse vignette with a new badge url.
+* fix a problem with app_deps on R 3.6.
 
 # pacs 0.5.1
 
diff --git a/R/deps.R b/R/deps.R
index f4c9207..0c7d178 100644
--- a/R/deps.R
+++ b/R/deps.R
@@ -254,7 +254,12 @@ app_deps <- function(path = ".",
       if (nrow(app_deps_recursive) == 0) {
         return(NA)
       }
-      app_deps_recursive <- stats::aggregate(app_deps_recursive[, c("Version"), drop = FALSE], list(Package = app_deps_recursive$Package), pacs::compareVersionsMax)
+      app_deps_recursive$Version <- as.character(app_deps_recursive$Version)
+      app_deps_recursive <- stats::aggregate(
+        app_deps_recursive[, c("Version"), drop = FALSE],
+        list(Package = app_deps_recursive$Package),
+        pacs::compareVersionsMax
+      )
       app_deps_recursive$Package <- as.character(app_deps_recursive$Package)
       app_deps_recursive$Direct <- app_deps_recursive$Package %in% app_deps
       return(app_deps_recursive)