diff --git a/Library/Homebrew/cask/installer.rb b/Library/Homebrew/cask/installer.rb
index 48c8a1e161..79ffc3dcc7 100644
--- a/Library/Homebrew/cask/installer.rb
+++ b/Library/Homebrew/cask/installer.rb
@@ -706,13 +706,17 @@ on_request: true)
         cask_and_formula_dependencies.each do |dep_cask_or_formula|
           dep_name, dep_type, variable = if dep_cask_or_formula.is_a?(Cask) && forbidden_casks.present?
             dep_cask = dep_cask_or_formula
-            dep_cask_name = if forbid_casks ||forbidden_casks.include?(dep_cask.token)
+            env_variable = "HOMEBREW_FORBIDDEN_CASKS"
+            dep_cask_name = if forbid_casks
+              env_variable = "HOMEBREW_FORBID_CASKS"
+              dep_cask.token
+            elsif forbidden_casks.include?(dep_cask.full_name)
               dep_cask.token
             elsif dep_cask.tap.present? &&
                   forbidden_casks.include?(dep_cask.full_name)
               dep_cask.full_name
             end
-            [dep_cask_name, "cask", "HOMEBREW_FORBIDDEN_CASKS"]
+            [dep_cask_name, "cask", env_variable]
           elsif dep_cask_or_formula.is_a?(Formula) && forbidden_formulae.present?
             dep_formula = dep_cask_or_formula
             formula_name = if forbidden_formulae.include?(dep_formula.name)
@@ -734,7 +738,11 @@ on_request: true)
       end
       return if !forbid_casks && forbidden_casks.blank?
 
-      if forbid_casks || forbidden_casks.include?(@cask.token)
+      variable = "HOMEBREW_FORBIDDEN_CASKS"
+      if forbid_casks
+        variable = "HOMEBREW_FORBID_CASKS"
+        @cask.token
+      elsif forbidden_casks.include?(@cask.token)
         @cask.token
       elsif forbidden_casks.include?(@cask.full_name)
         @cask.full_name
@@ -743,7 +751,7 @@ on_request: true)
       end
 
       raise CaskCannotBeInstalledError.new(@cask, <<~EOS
-        forbidden for installation by #{owner} in `HOMEBREW_FORBIDDEN_CASKS`.#{owner_contact}
+        forbidden for installation by #{owner} in `#{variable}`.#{owner_contact}
       EOS
       )
     end