diff --git a/ChangeLog b/ChangeLog
index 4aa624fa7..37b141e5d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2011-11-07  Richard Frith-Macdonald <rfm@gnu.org>
+
+	* Source/Additions/GSMime.m: ([+decodeBase64:]) tolerate missing
+	padding and also use of '-' and '_' rather than '+' and '/' as
+	permitted in the "URL and Filename safe" variation given in RFC 4648
+
 2011-11-04  Richard Frith-Macdonald <rfm@gnu.org>
 
 	* Source/NSDate.m:  ([-timeIntervalSinceDate:]) return NaN if other
diff --git a/Source/Additions/GSMime.m b/Source/Additions/GSMime.m
index 0a3171381..6a96954e2 100644
--- a/Source/Additions/GSMime.m
+++ b/Source/Additions/GSMime.m
@@ -4201,22 +4201,26 @@ appendString(NSMutableData *m, NSUInteger offset, NSUInteger fold,
 	{
 	  c = 63;
 	}
+      else if (c == '_')
+	{
+	  c = 63;	/* RFC 4648 permits '_' in URLs and filenames */
+	}
       else if (c == '+')
 	{
 	  c = 62;
 	}
+      else if (c == '-')
+	{
+	  c = 62;	/* RFC 4648 permits '-' in URLs and filenames */
+	}
       else if  (c == '=')
 	{
 	  c = -1;
 	  pad++;
 	}
-      else if (c == '-')
-	{
-	  break;		/* end    */
-	}
       else
 	{
-	  c = -1;		/* ignore */
+	  c = -1;	/* Ignore ... non-standard but more tolerant */
 	}
 
       if (c >= 0)
@@ -4231,6 +4235,15 @@ appendString(NSMutableData *m, NSUInteger offset, NSUInteger fold,
 	}
     }
 
+  /* If length is not a multiple of four, treat it as if the missing
+   * bytes were the '=' characters normally used for padding.
+   * This is not allowed by the basic standards, but permitted in some
+   * variants of 6ase64 encoding, so we should tolerate it.
+   */
+  if (length % 4 > 0)
+    {
+      pad += (4 - length % 4);
+    }
   if (pos > 0)
     {
       NSUInteger	i;
diff --git a/Tests/base/GSMime/general.m b/Tests/base/GSMime/general.m
index 799af4776..7d948c4ee 100644
--- a/Tests/base/GSMime/general.m
+++ b/Tests/base/GSMime/general.m
@@ -65,11 +65,22 @@ exact(GSMimeParser **parserPointer, NSData *data)
 int main()
 {
   NSAutoreleasePool   *arp = [NSAutoreleasePool new];
+  NSData *cr;
   NSData *data;
   GSMimeParser *parser;
   GSMimeDocument *doc;
   GSMimeDocument *idoc;
 
+  cr = [NSData dataWithBytes: "\r" length: 1];
+
+  data = [NSData dataWithBytes: "DQ==" length: 4];
+  PASS_EQUAL([GSMimeDocument decodeBase64: data], cr,
+    "decodeBase64 works for padded data");
+
+  data = [NSData dataWithBytes: "DQ" length: 2];
+  PASS_EQUAL([GSMimeDocument decodeBase64: data], cr,
+    "decodeBase64 works for unpadded data");
+
   data = [NSData dataWithContentsOfFile: @"mime1.dat"];
   idoc = exact(0, data);
   PASS_EQUAL([[[idoc content] objectAtIndex:0] content], @"a",