diff --git a/app/src/main/java/com/darkempire78/opencalculator/activities/MainActivity.kt b/app/src/main/java/com/darkempire78/opencalculator/activities/MainActivity.kt
index ea8c0777..dabebf51 100644
--- a/app/src/main/java/com/darkempire78/opencalculator/activities/MainActivity.kt
+++ b/app/src/main/java/com/darkempire78/opencalculator/activities/MainActivity.kt
@@ -973,6 +973,8 @@ class MainActivity : AppCompatActivity() {
 
             val calculation = binding.input.text.toString()
 
+            Expression().addParenthesis(calculation)
+
             if (calculation != "") {
 
                 val resultString = calculationResult.toString()
diff --git a/app/src/main/java/com/darkempire78/opencalculator/calculator/parser/Expression.kt b/app/src/main/java/com/darkempire78/opencalculator/calculator/parser/Expression.kt
index 9694d236..04a41c57 100644
--- a/app/src/main/java/com/darkempire78/opencalculator/calculator/parser/Expression.kt
+++ b/app/src/main/java/com/darkempire78/opencalculator/calculator/parser/Expression.kt
@@ -102,7 +102,7 @@ class Expression {
 
     }
 
-    private fun addParenthesis(calculation: String): String {
+    fun addParenthesis(calculation: String): String {
         // Add ")" which lack
         var cleanCalculation = calculation
         var openParentheses = 0
@@ -121,6 +121,10 @@ class Expression {
                 cleanCalculation += ')'
             }
         }
+        // Trigger syntax error if missing '('
+        if (closeParentheses > openParentheses) {
+            syntax_error = true
+        }
 
         return cleanCalculation
     }