diff --git a/NEWS b/NEWS
index 8f0000ff..d326dcef 100644
--- a/NEWS
+++ b/NEWS
@@ -38,6 +38,8 @@ Bugs that should be removed from NEWS before the 0.12.0 release:
was the first release that had these bugs.
* bug 1033: Fix memory leak in ECMAScript window.open. ELinks 0.12pre1
was the first release that had this bug.
+* bug 1034: ``Content-Encoding: deflate'' allows a zlib header as
+ specified in RFC 2616.
* Global ECMAScript functions alert, open, and setTimeout again work
with SEE. ELinks 0.12pre1 was the first release that supported SEE
at all.
diff --git a/src/encoding/deflate.c b/src/encoding/deflate.c
index f4b97f2a..aae2e299 100644
--- a/src/encoding/deflate.c
+++ b/src/encoding/deflate.c
@@ -125,6 +125,26 @@ deflate_read(struct stream_encoded *stream, unsigned char *buf, int len)
restart:
err = inflate(&data->deflate_stream, Z_SYNC_FLUSH);
if (err == Z_DATA_ERROR && !data->after_first_read) {
+ /* RFC 2616 requires a zlib header for
+ * "Content-Encoding: deflate", but some HTTP
+ * servers (Microsoft-IIS/6.0 at blogs.msdn.com,
+ * and reportedly Apache with mod_deflate) omit
+ * that, causing Z_DATA_ERROR. Clarification of
+ * the term "deflate" has been requested for the
+ * next version of HTTP:
+ * http://www3.tools.ietf.org/wg/httpbis/trac/ticket/73
+ *
+ * Try to recover by telling zlib not to expect
+ * the header. If the error does not happen on
+ * the first inflate() call, then it is too late
+ * to recover because ELinks may already have
+ * discarded part of the input data.
+ *
+ * TODO: This fallback to raw DEFLATE is currently
+ * enabled for "Content-Encoding: gzip" too. It
+ * might be better to fall back to no compression
+ * at all, because Apache can send that header for
+ * uncompressed *.gz.md5 files. */
data->after_first_read = 1;
inflateEnd(&data->deflate_stream);
data->deflate_stream.avail_out = len;
diff --git a/test/cgi/chunked_deflate.py b/test/cgi/chunked_deflate.py
index 5300c575..45f06828 100755
--- a/test/cgi/chunked_deflate.py
+++ b/test/cgi/chunked_deflate.py
@@ -1,11 +1,9 @@
#!/usr/bin/env python
-import os, time
-from zlib import *
+import os, time, zlib
data1 = 'Two lines should be visible.
The second line.'
-ob = compressobj(Z_DEFAULT_COMPRESSION, DEFLATED, -MAX_WBITS)
-cd1 = ob.compress(data1)
-cd1 += ob.flush()
+cd1 = zlib.compress(data1)
+
length = len(cd1)
next_chunk = hex(length - 10)[2:]
diff --git a/test/cgi/chunked_raw_deflate.py b/test/cgi/chunked_raw_deflate.py
new file mode 100755
index 00000000..6a762636
--- /dev/null
+++ b/test/cgi/chunked_raw_deflate.py
@@ -0,0 +1,22 @@
+#!/usr/bin/env python
+import os, time
+from zlib import *
+
+# According to section 3.5 of RFC 2616, "Content-Encoding: deflate"
+# requires a ZLIB header. However, Microsoft-IIS/6.0 sends a raw
+# DEFLATE stream instead. This CGI tests how ELinks handles that.
+
+data1 = 'Two lines should be visible.
The second line.'
+ob = compressobj(Z_DEFAULT_COMPRESSION, DEFLATED, -MAX_WBITS)
+cd1 = ob.compress(data1)
+cd1 += ob.flush()
+length = len(cd1)
+next_chunk = hex(length - 10)[2:]
+
+os.write(1, "Date: Sun, 20 Jan 2008 15:24:00 GMT\r\nServer: ddd\r\nTransfer-Encoding: chunked\r\nContent-Encoding: deflate\r\nConnection: close\r\nContent-Type: text/html; charset=ISO-8859-1\r\n")
+os.write(1, "\r\na\r\n")
+os.write(1, cd1[:10])
+time.sleep(2)
+os.write(1, "\r\n%s\r\n" % next_chunk)
+os.write(1, cd1[10:])
+os.write(1, "\r\n0\r\n")