diff --git a/k9mail/src/main/java/com/fsck/k9/message/PgpMessageBuilder.java b/k9mail/src/main/java/com/fsck/k9/message/PgpMessageBuilder.java
index 07245b0b5..e0563555f 100644
--- a/k9mail/src/main/java/com/fsck/k9/message/PgpMessageBuilder.java
+++ b/k9mail/src/main/java/com/fsck/k9/message/PgpMessageBuilder.java
@@ -39,8 +39,8 @@ import org.openintents.openpgp.util.OpenPgpApi.OpenPgpDataSource;
 
 
 public class PgpMessageBuilder extends MessageBuilder {
+    private static final int REQUEST_USER_INTERACTION = 1;
 
-    public static final int REQUEST_USER_INTERACTION = 1;
 
     private OpenPgpApi openPgpApi;
 
@@ -115,12 +115,16 @@ public class PgpMessageBuilder extends MessageBuilder {
                 throw new MessagingException("Attachments are not supported in PGP/INLINE format!");
             }
 
+            if (isPgpInlineMode && shouldSign && !shouldEncrypt) {
+                throw new UnsupportedOperationException("Clearsigning is not supported!");
+            }
+
             if (pgpApiIntent == null) {
                 pgpApiIntent = buildOpenPgpApiIntent(shouldSign, shouldEncrypt, isPgpInlineMode);
             }
 
             PendingIntent returnedPendingIntent = launchOpenPgpApiIntent(
-                    pgpApiIntent, shouldEncrypt || isPgpInlineMode, shouldEncrypt || !isPgpInlineMode, isPgpInlineMode);
+                    pgpApiIntent, shouldEncrypt, isPgpInlineMode);
             if (returnedPendingIntent != null) {
                 queueMessageBuildPendingIntent(returnedPendingIntent, REQUEST_USER_INTERACTION);
                 return;
@@ -170,7 +174,7 @@ public class PgpMessageBuilder extends MessageBuilder {
     }
 
     private PendingIntent launchOpenPgpApiIntent(@NonNull Intent openPgpIntent,
-            boolean captureOutputPart, boolean capturedOutputPartIs7Bit, boolean writeBodyContentOnly) throws MessagingException {
+            boolean captureOutputPart, boolean writeBodyContentOnly) throws MessagingException {
         final MimeBodyPart bodyPart = currentProcessedMimeMessage.toBodyPart();
         String[] contentType = currentProcessedMimeMessage.getHeader(MimeHeader.HEADER_CONTENT_TYPE);
         if (contentType.length > 0) {
@@ -183,8 +187,7 @@ public class PgpMessageBuilder extends MessageBuilder {
         OutputStream outputStream = null;
         if (captureOutputPart) {
             try {
-                pgpResultTempBody = new BinaryTempFileBody(
-                        capturedOutputPartIs7Bit ? MimeUtil.ENC_7BIT : MimeUtil.ENC_8BIT);
+                pgpResultTempBody = new BinaryTempFileBody(MimeUtil.ENC_7BIT);
                 outputStream = pgpResultTempBody.getOutputStream();
                 // OpenKeychain/BouncyCastle at this point use the system newline for formatting, which is LF on android.
                 // we need this to be CRLF, so we convert the data after receiving.
diff --git a/k9mail/src/test/java/com/fsck/k9/message/PgpMessageBuilderTest.java b/k9mail/src/test/java/com/fsck/k9/message/PgpMessageBuilderTest.java
index 10bab3661..87fa7e7da 100644
--- a/k9mail/src/test/java/com/fsck/k9/message/PgpMessageBuilderTest.java
+++ b/k9mail/src/test/java/com/fsck/k9/message/PgpMessageBuilderTest.java
@@ -343,8 +343,8 @@ public class PgpMessageBuilderTest {
         Assert.assertEquals(MimeUtil.ENC_7BIT, ((BinaryTempFileBody) message.getBody()).getEncoding());
     }
 
-    @Test
-    public void buildSign__withInlineEnabled__shouldSucceed() throws MessagingException {
+    @Test(expected = RuntimeException.class) // this is a wrapped UnsupportedOperationException from AsyncTask
+    public void buildSign__withInlineEnabled__shouldFail() throws MessagingException {
         ComposeCryptoStatus cryptoStatus = cryptoStatusBuilder
                 .setCryptoMode(CryptoMode.SIGN_ONLY)
                 .setRecipients(Collections.singletonList(new Recipient("test", "test@example.org", "labru", -1, "key")))
@@ -352,28 +352,8 @@ public class PgpMessageBuilderTest {
                 .build();
         pgpMessageBuilder.setCryptoStatus(cryptoStatus);
 
-        ArgumentCaptor<Intent> capturedApiIntent = ArgumentCaptor.forClass(Intent.class);
-
-        Intent returnIntent = new Intent();
-        returnIntent.putExtra(OpenPgpApi.RESULT_CODE, OpenPgpApi.RESULT_CODE_SUCCESS);
-
-        when(openPgpApi.executeApi(capturedApiIntent.capture(), any(OpenPgpDataSource.class), any(OutputStream.class)))
-                .thenReturn(returnIntent);
-
         Callback mockCallback = mock(Callback.class);
         pgpMessageBuilder.buildAsync(mockCallback);
-
-        Intent expectedApiIntent = new Intent(OpenPgpApi.ACTION_SIGN);
-        expectedApiIntent.putExtra(OpenPgpApi.EXTRA_SIGN_KEY_ID, TEST_SIGN_KEY_ID);
-        expectedApiIntent.putExtra(OpenPgpApi.EXTRA_REQUEST_ASCII_ARMOR, true);
-        assertIntentEqualsActionAndExtras(expectedApiIntent, capturedApiIntent.getValue());
-
-        ArgumentCaptor<MimeMessage> captor = ArgumentCaptor.forClass(MimeMessage.class);
-        verify(mockCallback).onMessageBuildSuccess(captor.capture(), eq(false));
-        verifyNoMoreInteractions(mockCallback);
-
-        MimeMessage message = captor.getValue();
-        Assert.assertEquals("message must be text/plain", "text/plain", message.getMimeType());
     }
 
     @Test