diff --git a/app/src/main/java/org/koitharu/kotatsu/core/network/CommonHeadersInterceptor.kt b/app/src/main/java/org/koitharu/kotatsu/core/network/CommonHeadersInterceptor.kt
index 7b26a9d71..6896cc4ab 100644
--- a/app/src/main/java/org/koitharu/kotatsu/core/network/CommonHeadersInterceptor.kt
+++ b/app/src/main/java/org/koitharu/kotatsu/core/network/CommonHeadersInterceptor.kt
@@ -3,6 +3,7 @@ package org.koitharu.kotatsu.core.network
 import android.os.Build
 import android.util.Log
 import dagger.Lazy
+import okhttp3.Headers
 import okhttp3.Interceptor
 import okhttp3.Request
 import okhttp3.Response
@@ -11,6 +12,7 @@ import org.koitharu.kotatsu.core.parser.MangaRepository
 import org.koitharu.kotatsu.core.parser.RemoteMangaRepository
 import org.koitharu.kotatsu.parsers.model.MangaSource
 import org.koitharu.kotatsu.parsers.util.mergeWith
+import org.koitharu.kotatsu.utils.ext.printStackTraceDebug
 import java.util.Locale
 import javax.inject.Inject
 import javax.inject.Singleton
@@ -39,12 +41,18 @@ class CommonHeadersInterceptor @Inject constructor(
 			headersBuilder[CommonHeaders.USER_AGENT] = userAgentFallback
 		}
 		if (headersBuilder[CommonHeaders.REFERER] == null && repository != null) {
-			headersBuilder[CommonHeaders.REFERER] = "https://${repository.domain}/"
+			headersBuilder.trySet(CommonHeaders.REFERER, "https://${repository.domain}/")
 		}
 		val newRequest = request.newBuilder().headers(headersBuilder.build()).build()
 		return repository?.intercept(ProxyChain(chain, newRequest)) ?: chain.proceed(newRequest)
 	}
 
+	private fun Headers.Builder.trySet(name: String, value: String) = try {
+		set(name, value)
+	} catch (e: IllegalArgumentException) {
+		e.printStackTraceDebug()
+	}
+
 	private class ProxyChain(
 		private val delegate: Interceptor.Chain,
 		private val request: Request,
diff --git a/app/src/main/java/org/koitharu/kotatsu/settings/DomainValidator.kt b/app/src/main/java/org/koitharu/kotatsu/settings/DomainValidator.kt
index 6fc5adab3..a5f50c968 100644
--- a/app/src/main/java/org/koitharu/kotatsu/settings/DomainValidator.kt
+++ b/app/src/main/java/org/koitharu/kotatsu/settings/DomainValidator.kt
@@ -7,14 +7,24 @@ import org.koitharu.kotatsu.utils.EditTextValidator
 class DomainValidator : EditTextValidator() {
 
 	override fun validate(text: String): ValidationResult {
-		if (text.isBlank()) {
+		val trimmed = text.trim()
+		if (trimmed.isEmpty()) {
 			return ValidationResult.Success
 		}
-		val host = text.trim().toCanonicalHost()
-		return if (host == null) {
+		return if (!checkCharacters(trimmed) || trimmed.toCanonicalHost() == null) {
 			ValidationResult.Failed(context.getString(R.string.invalid_domain_message))
 		} else {
 			ValidationResult.Success
 		}
 	}
-}
\ No newline at end of file
+
+	private fun checkCharacters(value: String): Boolean {
+		for (i in value.indices) {
+			val c = value[i]
+			if (c !in '\u0020'..'\u007e') {
+				return false
+			}
+		}
+		return true
+	}
+}