diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/connector/TrimmingInputStream.java b/acme4j-client/src/main/java/org/shredzone/acme4j/connector/TrimmingInputStream.java
index 29e29f68..e670dd33 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/connector/TrimmingInputStream.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/connector/TrimmingInputStream.java
@@ -13,17 +13,18 @@
  */
 package org.shredzone.acme4j.connector;
 
+import java.io.BufferedInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 
 /**
  * Normalizes line separators in an InputStream. Converts all line separators to '\n'.
- * Multiple line separators are compressed to a single line separator.
+ * Multiple line separators are compressed to a single line separator. Leading line
+ * separators are removed. Trailing line separators are compressed to a single separator.
  */
 public class TrimmingInputStream extends InputStream {
-
-    private final InputStream in;
-    private boolean wasLineSeparator = true;
+    private final BufferedInputStream in;
+    private boolean startOfFile = true;
 
     /**
      * Creates a new {@link TrimmingInputStream}.
@@ -33,26 +34,50 @@ public class TrimmingInputStream extends InputStream {
      *            closed.
      */
     public TrimmingInputStream(InputStream in) {
-        this.in = in;
+        this.in = new BufferedInputStream(in, 1024);
     }
 
     @Override
     public int read() throws IOException {
         int ch = in.read();
 
-        if (wasLineSeparator) {
-            while (isLineSeparator(ch)) {
-                ch = in.read();
+        if (!isLineSeparator(ch)) {
+            startOfFile = false;
+            return ch;
+        }
+
+        in.mark(1);
+        ch = in.read();
+        while (isLineSeparator(ch)) {
+            in.mark(1);
+            ch = in.read();
+        }
+
+        if (startOfFile) {
+            startOfFile = false;
+            return ch;
+        } else {
+            in.reset();
+            return '\n';
+        }
+    }
+
+    @Override
+    public int available() throws IOException {
+        // Workaround for https://github.com/google/conscrypt/issues/1068. Conscrypt
+        // requires the stream to have at least one non-blocking byte available for
+        // reading, otherwise generateCertificates() will not read the stream, but
+        // immediately returns an empty list. This workaround pre-fills the buffer
+        // of the BufferedInputStream by reading 1 byte ahead.
+        if (in.available() == 0) {
+            in.mark(1);
+            int read = in.read();
+            in.reset();
+            if (read < 0) {
+                return 0;
             }
         }
-
-        wasLineSeparator = isLineSeparator(ch);
-
-        if (ch == '\r') {
-            ch = '\n';
-        }
-
-        return ch;
+        return in.available();
     }
 
     @Override
diff --git a/acme4j-client/src/test/java/org/shredzone/acme4j/connector/TrimmingInputStreamTest.java b/acme4j-client/src/test/java/org/shredzone/acme4j/connector/TrimmingInputStreamTest.java
index d57fa9fb..8d88e181 100644
--- a/acme4j-client/src/test/java/org/shredzone/acme4j/connector/TrimmingInputStreamTest.java
+++ b/acme4j-client/src/test/java/org/shredzone/acme4j/connector/TrimmingInputStreamTest.java
@@ -15,6 +15,7 @@ package org.shredzone.acme4j.connector;
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.not;
 
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
@@ -26,6 +27,15 @@ import org.junit.Test;
  * Unit tests for {@link TrimmingInputStream}.
  */
 public class TrimmingInputStreamTest {
+    private final static String FULL_TEXT =
+              "Gallia est omnis divisa in partes tres,\r\n\r\n\r\n"
+            + "quarum unam incolunt Belgae, aliam Aquitani,\r\r\r\n\n"
+            + "tertiam, qui ipsorum lingua Celtae, nostra Galli appellantur.";
+
+    private final static String TRIMMED_TEXT =
+              "Gallia est omnis divisa in partes tres,\n"
+            + "quarum unam incolunt Belgae, aliam Aquitani,\n"
+            + "tertiam, qui ipsorum lingua Celtae, nostra Galli appellantur.";
 
     @Test
     public void testEmpty() throws IOException {
@@ -33,15 +43,48 @@ public class TrimmingInputStreamTest {
         assertThat(out, is(""));
     }
 
+    @Test
+    public void testLineBreakOnly() throws IOException {
+        String out1 = trimByStream("\n");
+        assertThat(out1, is(""));
+
+        String out2 = trimByStream("\r");
+        assertThat(out2, is(""));
+
+        String out3 = trimByStream("\r\n");
+        assertThat(out2, is(""));
+    }
+
     @Test
     public void testTrim() throws IOException {
-        String out = trimByStream("\n\n"
-            + "Gallia est omnis divisa in partes tres,\r\n\r\n\r\n"
-            + "quarum unam incolunt Belgae, aliam Aquitani,\r\r\r\n\n"
-            + "tertiam, qui ipsorum lingua Celtae, nostra Galli appellantur.");
-        assertThat(out, is("Gallia est omnis divisa in partes tres,\n"
-            + "quarum unam incolunt Belgae, aliam Aquitani,\n"
-            + "tertiam, qui ipsorum lingua Celtae, nostra Galli appellantur."));
+        String out = trimByStream(FULL_TEXT);
+        assertThat(out, is(TRIMMED_TEXT));
+    }
+
+    @Test
+    public void testTrimEndOnly() throws IOException {
+        String out = trimByStream(FULL_TEXT + "\r\n\r\n");
+        assertThat(out, is(TRIMMED_TEXT + "\n"));
+    }
+
+    @Test
+    public void testTrimStartOnly() throws IOException {
+        String out = trimByStream("\n\n" + FULL_TEXT);
+        assertThat(out, is(TRIMMED_TEXT));
+    }
+
+    @Test
+    public void testTrimFull() throws IOException {
+        String out = trimByStream("\n\n" + FULL_TEXT + "\r\n\r\n");
+        assertThat(out, is(TRIMMED_TEXT + "\n"));
+    }
+
+    @Test
+    public void testAvailable() throws IOException {
+        try (TrimmingInputStream in = new TrimmingInputStream(
+                new ByteArrayInputStream("Test".getBytes(StandardCharsets.US_ASCII)))) {
+            assertThat(in.available(), not(0));
+        }
     }
 
     /**