diff --git a/feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/TextFieldController.kt b/feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/TextFieldController.kt
index 61e724d9..d1cb5ed2 100644
--- a/feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/TextFieldController.kt
+++ b/feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/TextFieldController.kt
@@ -20,11 +20,43 @@ package com.sadellie.unitto.feature.calculator
 
 import androidx.compose.ui.text.TextRange
 import androidx.compose.ui.text.input.TextFieldValue
+import com.sadellie.unitto.core.base.KEY_0
+import com.sadellie.unitto.core.base.KEY_1
+import com.sadellie.unitto.core.base.KEY_2
+import com.sadellie.unitto.core.base.KEY_3
+import com.sadellie.unitto.core.base.KEY_4
+import com.sadellie.unitto.core.base.KEY_5
+import com.sadellie.unitto.core.base.KEY_6
+import com.sadellie.unitto.core.base.KEY_7
+import com.sadellie.unitto.core.base.KEY_8
+import com.sadellie.unitto.core.base.KEY_9
+import com.sadellie.unitto.core.base.KEY_BASE_A
+import com.sadellie.unitto.core.base.KEY_BASE_B
+import com.sadellie.unitto.core.base.KEY_BASE_C
+import com.sadellie.unitto.core.base.KEY_BASE_D
+import com.sadellie.unitto.core.base.KEY_BASE_E
+import com.sadellie.unitto.core.base.KEY_BASE_F
 import com.sadellie.unitto.core.base.KEY_COS
+import com.sadellie.unitto.core.base.KEY_DIVIDE
+import com.sadellie.unitto.core.base.KEY_DIVIDE_DISPLAY
 import com.sadellie.unitto.core.base.KEY_DOT
+import com.sadellie.unitto.core.base.KEY_EXPONENT
+import com.sadellie.unitto.core.base.KEY_E_SMALL
+import com.sadellie.unitto.core.base.KEY_FACTORIAL
+import com.sadellie.unitto.core.base.KEY_LEFT_BRACKET
 import com.sadellie.unitto.core.base.KEY_LN
 import com.sadellie.unitto.core.base.KEY_LOG
+import com.sadellie.unitto.core.base.KEY_MINUS
+import com.sadellie.unitto.core.base.KEY_MINUS_DISPLAY
+import com.sadellie.unitto.core.base.KEY_MODULO
+import com.sadellie.unitto.core.base.KEY_MULTIPLY
+import com.sadellie.unitto.core.base.KEY_MULTIPLY_DISPLAY
+import com.sadellie.unitto.core.base.KEY_PERCENT
+import com.sadellie.unitto.core.base.KEY_PI
+import com.sadellie.unitto.core.base.KEY_PLUS
+import com.sadellie.unitto.core.base.KEY_RIGHT_BRACKET
 import com.sadellie.unitto.core.base.KEY_SIN
+import com.sadellie.unitto.core.base.KEY_SQRT
 import com.sadellie.unitto.core.base.KEY_TAN
 import com.sadellie.unitto.core.ui.UnittoFormatter
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -33,6 +65,8 @@ import javax.inject.Inject
 import kotlin.math.abs
 
 class TextFieldController @Inject constructor() {
+    var input: MutableStateFlow<TextFieldValue> = MutableStateFlow(TextFieldValue())
+
     // Internally we don't care about user preference here, because during composition this
     // symbols will be replaced to those that user wanted.
     // We do this because it adds unnecessary logic: it requires additional logic to observe and
@@ -46,7 +80,19 @@ class TextFieldController @Inject constructor() {
 
     private val cursorFixer by lazy { CursorFixer() }
 
-    var input: MutableStateFlow<TextFieldValue> = MutableStateFlow(TextFieldValue())
+    private val knownSymbols: List<String> by lazy {
+        listOf(
+            KEY_SIN, KEY_COS, KEY_TAN, KEY_LN, KEY_LOG,
+            KEY_LEFT_BRACKET, KEY_RIGHT_BRACKET,
+            KEY_EXPONENT, KEY_SQRT, KEY_FACTORIAL,
+            KEY_MODULO, KEY_E_SMALL, KEY_PERCENT, KEY_PI,
+            KEY_MULTIPLY, KEY_MULTIPLY_DISPLAY,
+            KEY_PLUS, KEY_MINUS, KEY_MINUS_DISPLAY, KEY_DIVIDE, KEY_DIVIDE_DISPLAY,
+            KEY_BASE_A, KEY_BASE_B, KEY_BASE_C, KEY_BASE_D, KEY_BASE_E, KEY_BASE_F,
+            KEY_1, KEY_2, KEY_3, KEY_4, KEY_5, KEY_6, KEY_7, KEY_8, KEY_9, KEY_0,
+            KEY_DOT,
+        )
+    }
 
     fun addToInput(symbols: String) {
 
@@ -71,6 +117,11 @@ class TextFieldController @Inject constructor() {
         }
     }
 
+    /**
+     * Method to call when pasting from clipbaord. It filters input before calling [addToInput].
+     */
+    fun pasteSymbols(symbols: String) = addToInput(symbols.filterUnknownSymbols())
+
     fun moveCursor(newPosition: IntRange) {
         val currentInput = input.value.text
         val fixedLeftCursor = cursorFixer.fixCursorIfNeeded(currentInput, newPosition.first)
@@ -126,6 +177,28 @@ class TextFieldController @Inject constructor() {
 
     private fun String.fixFormat(): String = localFormatter.reFormat(this)
 
+    private fun String.filterUnknownSymbols(): String {
+        var clearStr = this.replace(" ", "")
+        var garbage = clearStr
+
+        // String with unknown symbols
+        knownSymbols.forEach {
+            garbage = garbage.replace(it, " ")
+        }
+
+        // Remove unknown symbols from input
+        garbage.split(" ").forEach {
+            clearStr = clearStr.replace(it, "")
+        }
+
+        clearStr = clearStr
+            .replace(KEY_DIVIDE, KEY_DIVIDE_DISPLAY)
+            .replace(KEY_MULTIPLY, KEY_MULTIPLY_DISPLAY)
+            .replace(KEY_MINUS, KEY_MINUS_DISPLAY)
+
+        return clearStr
+    }
+
     inner class CursorFixer {
         val illegalTokens by lazy {
             listOf(
diff --git a/feature/calculator/src/test/java/com/sadellie/unitto/feature/calculator/TextFieldControllerTest.kt b/feature/calculator/src/test/java/com/sadellie/unitto/feature/calculator/TextFieldControllerTest.kt
index 2f76a956..978946b1 100644
--- a/feature/calculator/src/test/java/com/sadellie/unitto/feature/calculator/TextFieldControllerTest.kt
+++ b/feature/calculator/src/test/java/com/sadellie/unitto/feature/calculator/TextFieldControllerTest.kt
@@ -189,7 +189,7 @@ internal class TextFieldControllerTest {
     }
 
     @Test
-    fun `placed cursor illegally`() {
+    fun `Place cursor illegally`() {
         textFieldController.addToInput("123456.789")
         // Input is 123,456.789
         textFieldController.moveCursor(4..4)
@@ -211,4 +211,34 @@ internal class TextFieldControllerTest {
         // Input is 123,456.789
         assertEquals("123456.789+cos(..)", textFieldController.inputTextWithoutFormatting())
     }
+
+    @Test
+    fun `Paste completely weird stuff`() {
+        textFieldController.pasteSymbols("crazy stuff from clipboard")
+        assertEquals("", textFieldController.text)
+    }
+
+    @Test
+    fun `Paste partially weird stuff`() {
+        textFieldController.pasteSymbols("some crazy stuff cos(8+9)*7= that user may have in clipboard")
+        assertEquals("ecos(8+9)×7ee", textFieldController.text)
+    }
+
+    @Test
+    fun `Paste acceptable stuff that needs symbol replacement`() {
+        textFieldController.pasteSymbols("cos(8+9)*7")
+        assertEquals("cos(8+9)×7", textFieldController.text)
+    }
+
+    @Test
+    fun `Paste acceptable stuff that does not need replacement`() {
+        textFieldController.pasteSymbols("cos(8+9)×7")
+        assertEquals("cos(8+9)×7", textFieldController.text)
+    }
+
+    @Test
+    fun `Paste nothing`() {
+        textFieldController.pasteSymbols("")
+        assertEquals("", textFieldController.text)
+    }
 }