diff --git a/library/base64.c b/library/base64.c
index 05b2d80..139c5cc 100644
--- a/library/base64.c
+++ b/library/base64.c
@@ -72,7 +72,10 @@
     unsigned char *p;
 
     if( slen == 0 )
+    {
+        *dlen = 0;
         return( 0 );
+    }
 
     n = (slen << 3) / 6;