From: David Bremner <bremner@debian.org>

The pointer returned by g_mime_utils_header_decode_text is from the
following line in rfc2047_decode_tokens

	return g_string_free (decoded, FALSE);

The docs for g_string_free say

 Frees the memory allocated for the GString. If free_segment is TRUE
 it also frees the character data. If it's FALSE, the caller gains
 ownership of the buffer and must free it after use with g_free().
---
 lib/message-file.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/message-file.c b/lib/message-file.c
index 915aba8..976769d 100644
--- a/lib/message-file.c
+++ b/lib/message-file.c
@@ -341,7 +341,7 @@ notmuch_message_file_get_header (notmuch_message_file_t *message,
 		strncpy(combined_header,header_sofar,hdrsofar);
 		*(combined_header+hdrsofar) = ' ';
 		strncpy(combined_header+hdrsofar+1,decoded_value,newhdr+1);
-		free (decoded_value);
+		g_free (decoded_value);
 		g_hash_table_insert (message->headers, header, combined_header);
 	    }
 	} else {
@@ -350,7 +350,7 @@ notmuch_message_file_get_header (notmuch_message_file_t *message,
 		g_hash_table_insert (message->headers, header, decoded_value);
 	    } else {
 		free (header);
-		free (decoded_value);
+		g_free (decoded_value);
 		decoded_value = header_sofar;
 	    }
 	}
-- 
1.7.10.4