diff --git a/phpmon/Domain/Integrations/Homebrew/BrewPhpFormula.swift b/phpmon/Domain/Integrations/Homebrew/BrewPhpFormula.swift
index 7930005..2236a33 100644
--- a/phpmon/Domain/Integrations/Homebrew/BrewPhpFormula.swift
+++ b/phpmon/Domain/Integrations/Homebrew/BrewPhpFormula.swift
@@ -21,8 +21,6 @@ struct BrewPhpFormula: Equatable {
     /// The upgrade that is currently available, if it exists.
     let upgradeVersion: String?
 
-    // TODO: A rebuild attribute could be checked, to check if a Tap update exists for a pre-release version
-
     /// Whether this formula is a stable version of PHP.
     let prerelease: Bool
 
@@ -49,6 +47,16 @@ struct BrewPhpFormula: Equatable {
     var hasUpgrade: Bool {
         return upgradeVersion != nil
     }
+    
+    var hasFormulaFile: Bool {
+        guard let version = shortVersion else {
+            return false
+        }
+        
+        return FileSystem.fileExists(
+            "\(Paths.tapPath)/shivammathur/homebrew-php/Formula/php@\(version).rb"
+        )
+    }
 
     /// Whether this formula alias is different.
     var hasUpgradedFormulaAlias: Bool {
diff --git a/phpmon/Modules/PHP Version Manager/UI/PhpVersionManagerView.swift b/phpmon/Modules/PHP Version Manager/UI/PhpVersionManagerView.swift
index 6b9e191..23b4256 100644
--- a/phpmon/Modules/PHP Version Manager/UI/PhpVersionManagerView.swift	
+++ b/phpmon/Modules/PHP Version Manager/UI/PhpVersionManagerView.swift	
@@ -238,7 +238,7 @@ struct PhpVersionManagerView: View {
             } else {
                 Button("phpman.buttons.install".localizedForSwiftUI) {
                     Task { await self.install(formula) }
-                }.disabled(formula.hasUpgradedFormulaAlias)
+                }.disabled(formula.hasUpgradedFormulaAlias || !formula.hasFormulaFile)
             }
         }
     }
@@ -268,6 +268,17 @@ struct PhpVersionManagerView: View {
                 Text("phpman.version.installed".localized(formula.installedVersion!))
                     .font(.system(size: 11))
                     .foregroundColor(.gray)
+            } else if !formula.hasFormulaFile {
+                HStack(spacing: 5) {
+                    Text("phpman.version.unavailable".localizedForSwiftUI)
+                        .font(.system(size: 11))
+                        .foregroundColor(.gray)
+                    HelpButton(action: {
+                        // Show an alert that displays information about the missing formula
+                        // and what can be done to fix this particular issue.
+                        // Running `brew tap shivammathur/php` generally works, I think.
+                    })
+                }
             } else {
                 Text("phpman.version.available_for_installation".localizedForSwiftUI)
                     .font(.system(size: 11))
diff --git a/phpmon/en.lproj/Localizable.strings b/phpmon/en.lproj/Localizable.strings
index b27ce4e..ba633e0 100644
--- a/phpmon/en.lproj/Localizable.strings
+++ b/phpmon/en.lproj/Localizable.strings
@@ -138,6 +138,7 @@ and restart PHP Monitor for extensions to become visible. If the problem persist
 "phpman.version.has_update" = "Version %@ installed, %@ available.";
 "phpman.version.installed" = "Version %@ is currently installed.";
 "phpman.version.available_for_installation" = "This version can be installed.";
+"phpman.version.unavailable" = "This version is temporarily unavailable.";
 "phpman.version.automatic_upgrade" = "This version will be automatically installed by upgrading an older version.";
 "phpman.buttons.uninstall" = "Uninstall";
 "phpman.buttons.install" = "Install";