diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/login/symbol/LoginSymbolFragment.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/login/symbol/LoginSymbolFragment.kt
index 692aaeb7..67957659 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/login/symbol/LoginSymbolFragment.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/login/symbol/LoginSymbolFragment.kt
@@ -100,6 +100,13 @@ class LoginSymbolFragment :
         }
     }
 
+    override fun setErrorSymbolDefinitelyInvalid() {
+        with(binding.loginSymbolNameLayout) {
+            requestFocus()
+            error = getString(R.string.login_invalid_symbol_definitely)
+        }
+    }
+
     override fun setErrorSymbolRequire() {
         setErrorSymbol(getString(R.string.error_field_required))
     }
diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/login/symbol/LoginSymbolPresenter.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/login/symbol/LoginSymbolPresenter.kt
index 91fe1ac3..01855fce 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/login/symbol/LoginSymbolPresenter.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/login/symbol/LoginSymbolPresenter.kt
@@ -53,6 +53,10 @@ class LoginSymbolPresenter @Inject constructor(
             view?.setErrorSymbolRequire()
             return
         }
+        if (isFormDefinitelyInvalid()) {
+            view?.setErrorSymbolDefinitelyInvalid()
+            return
+        }
 
         loginData = loginData.copy(
             symbol = view?.symbolValue?.getNormalizedSymbol(),
@@ -130,6 +134,13 @@ class LoginSymbolPresenter @Inject constructor(
         }.launch("login")
     }
 
+    private fun isFormDefinitelyInvalid(): Boolean {
+        val definitelyInvalidSymbols = listOf("vulcan", "uonet", "wulkanowy", "standardowa")
+        val normalizedSymbol = view?.symbolValue.orEmpty().getNormalizedSymbol()
+
+        return normalizedSymbol in definitelyInvalidSymbols
+    }
+
     fun onFaqClick() {
         view?.openFaqPage()
     }
diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/login/symbol/LoginSymbolView.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/login/symbol/LoginSymbolView.kt
index 6585c00f..3c10d574 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/login/symbol/LoginSymbolView.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/login/symbol/LoginSymbolView.kt
@@ -18,6 +18,8 @@ interface LoginSymbolView : BaseView {
 
     fun setErrorSymbolInvalid()
 
+    fun setErrorSymbolDefinitelyInvalid()
+
     fun setErrorSymbolRequire()
 
     fun setErrorSymbol(message: String)
diff --git a/app/src/main/res/layout/fragment_login_symbol.xml b/app/src/main/res/layout/fragment_login_symbol.xml
index d928d65f..37f4c731 100644
--- a/app/src/main/res/layout/fragment_login_symbol.xml
+++ b/app/src/main/res/layout/fragment_login_symbol.xml
@@ -141,7 +141,9 @@
                 app:layout_constraintEnd_toEndOf="parent"
                 app:layout_constraintHorizontal_bias="0.5"
                 app:layout_constraintStart_toStartOf="parent"
-                app:layout_constraintTop_toBottomOf="@+id/loginSymbolHelper">
+                app:layout_constraintTop_toBottomOf="@+id/loginSymbolHelper"
+                app:placeholderText="@string/login_symbol_placeholder"
+                app:placeholderTextColor="?colorTertiary">
 
                 <AutoCompleteTextView
                     android:id="@+id/loginSymbolName"
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 7da41b3d..df40fe70 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -49,6 +49,7 @@
     <string name="login_token_hint">Token</string>
     <string name="login_pin_hint">PIN</string>
     <string name="login_symbol_hint">Symbol</string>
+    <string name="login_symbol_placeholder">E.g. \"lodz\" or \"powiatjaroslawski\"</string>
     <string name="login_sign_in">Sign in</string>
     <string name="login_invalid_password">Password too short</string>
     <string name="login_incorrect_password_default">Login details are incorrect</string>
@@ -59,7 +60,8 @@
     <string name="login_invalid_email">Invalid email</string>
     <string name="login_invalid_login">Use the assigned login instead of email</string>
     <string name="login_invalid_custom_email">Use the assigned login or email in @%1$s</string>
-    <string name="login_invalid_symbol">Invalid symbol</string>
+    <string name="login_invalid_symbol">Invalid symbol. If you cannot find it, please contact the school</string>
+    <string name="login_invalid_symbol_definitely">Don\'t make this up! If you cannot find it, please contact the school</string>
     <string name="login_incorrect_symbol">Student not found. Validate the symbol and the chosen variation of the UONET+ register</string>
     <string name="login_duplicate_student">Selected student is already logged in</string>
     <string name="login_symbol_helper">The symbol can be found on the register page in&#160;<b>Uczeń</b> →&#160;<b>Dostęp Mobilny</b> →&#160;<b>Wygeneruj kod dostępu</b>.\n\nMake sure that you have set the appropriate register variant in the <b>UONET+ register variant</b> field on the first login screen</string>