diff --git a/lib/device_detector.rb b/lib/device_detector.rb
index 9e9d37b..a0b4be8 100644
--- a/lib/device_detector.rb
+++ b/lib/device_detector.rb
@@ -21,7 +21,8 @@ class DeviceDetector
 
   def initialize(user_agent, headers = nil)
     @client_hint = ClientHint.new(headers)
-    @user_agent = set_user_agent(user_agent)
+    utf8_user_agent = encode_user_agent_if_needed(user_agent)
+    @user_agent = set_user_agent(utf8_user_agent)
   end
 
   # https://github.com/matomo-org/device-detector/blob/c235832dba13961ab0f71b681616baf1aa48de23/Parser/Device/AbstractDeviceParser.php#L1873
@@ -36,6 +37,13 @@ def set_user_agent(user_agent)
     user_agent.gsub(regex, "Android #{version}, #{client_hint.model}")
   end
 
+  def encode_user_agent_if_needed(user_agent)
+    return if user_agent.nil?
+    return user_agent if user_agent.encoding.name == 'UTF-8'
+
+    user_agent.encode('utf-8', 'binary', undef: :replace)
+  end
+
   def name
     return client.name if mobile_fix?
 
diff --git a/spec/device_detector_spec.rb b/spec/device_detector_spec.rb
index 5967aa2..8164409 100644
--- a/spec/device_detector_spec.rb
+++ b/spec/device_detector_spec.rb
@@ -9,7 +9,9 @@
 
   describe 'known user agent' do
     describe 'desktop chrome browser' do
-      let(:user_agent) { 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/30.0.1599.69' }
+      let(:user_agent) do
+        'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/30.0.1599.69'
+      end
 
       describe '#name' do
         it 'returns the name' do
@@ -141,6 +143,52 @@
     end
   end
 
+  describe 'wrongly encoded user agent' do
+    let(:user_agent) { 'Mon User-Agent personnalisé'.dup.force_encoding('ASCII-8BIT') }
+
+    describe '#name' do
+      it 'returns nil' do
+        value(client.name).must_be_nil
+      end
+    end
+
+    describe '#full_version' do
+      it 'returns nil' do
+        value(client.full_version).must_be_nil
+      end
+    end
+
+    describe '#os_name' do
+      it 'returns nil' do
+        value(client.os_name).must_be_nil
+      end
+    end
+
+    describe '#os_full_version' do
+      it 'returns nil' do
+        value(client.os_full_version).must_be_nil
+      end
+    end
+
+    describe '#known?' do
+      it 'returns false' do
+        value(client.known?).must_equal false
+      end
+    end
+
+    describe '#bot?' do
+      it 'returns false' do
+        value(client.bot?).must_equal false
+      end
+    end
+
+    describe '#bot_name' do
+      it 'returns nil' do
+        value(client.bot_name).must_be_nil
+      end
+    end
+  end
+
   describe 'bot' do
     let(:user_agent) { 'Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)' }