diff --git a/README.md b/README.md
index 35184a2d7e1a6531d8b840c101e43b68091c64a8..ce61e550e01fb8e5f70976a333d71ff31d7a43c3 100644
--- a/README.md
+++ b/README.md
@@ -181,5 +181,4 @@ module "webapp" {
 Originally, the module did not deploy images except on the very first use (using
 `gcr.io/cloudrun/hello:latest`).
 
-Currently, the module deploys the image from `image_name` if specified, otherwise keep the
-current image, if that doesn't exist fall-back to the "hello" image.
+Currently, the module deploys the image from the mandatory variable `image_name`.
diff --git a/locals.tf b/locals.tf
index 07c2f120a4d1717eed2897d20cef31429482bca7..ce0b188ba911aa7a69fb843aec59e06d4b73be2b 100644
--- a/locals.tf
+++ b/locals.tf
@@ -51,11 +51,4 @@ locals {
     [trimsuffix(trimprefix(google_cloud_run_service.webapp.status[0].url, "https://"), "/")],
     var.allow_unauthenticated_invocations ? local.dns_names : [],
   )
-
-  # If a cloud run revision is present, get the full URL of the deployed image.
-  existing_image_name = (
-    data.google_cloud_run_service.webapp.template != null ?
-    data.google_cloud_run_service.webapp.template[0].spec[0].containers[0].image :
-    ""
-  )
 }
diff --git a/main.tf b/main.tf
index 99ff371ac769354996248d40e1017d389aca831c..1a0923c04bbeda74e5493df4e3c5ed67e4aa8306 100644
--- a/main.tf
+++ b/main.tf
@@ -111,11 +111,7 @@ resource "google_cloud_run_service" "webapp" {
       service_account_name = google_service_account.webapp.email
 
       containers {
-        image = coalesce(
-          var.image_name,
-          local.existing_image_name,
-          "gcr.io/cloudrun/hello:latest",
-        )
+        image = var.image_name
 
         resources {
           limits = {
diff --git a/variables.tf b/variables.tf
index 27b9a281ee243f5a56c28a6239c76fabc701d109..8940782fbc3998ea048eb92005be20470e9367a4 100644
--- a/variables.tf
+++ b/variables.tf
@@ -306,9 +306,9 @@ EOL
 
 variable "image_name" {
   type        = string
-  default     = ""
-  description = <<-EOL
-    Optional. The docker image that will be deployed. If unset, the value of
-    existing_image_name is preferred.
-EOL
+  description = "The URL of the container image to be deployed."
+  validation {
+    condition     = length(var.image_name) > 0
+    error_message = "The image_name value must be a valid URL to a container image."
+  }
 }