diff --git a/lib/base64.c b/lib/base64.c
index e29a765..a1333a7 100644
--- a/lib/base64.c
+++ b/lib/base64.c
@@ -21,6 +21,7 @@
 
 #include <stdint.h>
 #include <stdlib.h>
+#include <string.h>
 #include <sys/types.h>
 
 #include <sxmp/base64.h>
@@ -35,16 +36,29 @@ static inline void encodeblock(unsigned char *in, unsigned char *out, int len)
   out[3] = (unsigned char) (len > 2 ? b64[ (int)(in[2] & 0x3f) ] : '=');
 }
 
+static inline char __block(char b)
+{
+  const char *j = strchr(b64, b);
+
+  if(j) return j - b64;
+  else return 0;
+}
+
 static inline void decodeblock(unsigned char *in, unsigned char *out)
 {
-  out[0] = (unsigned char) (in[0] << 2 | in[1] >> 4);
-  out[1] = (unsigned char) (in[1] << 4 | in[2] >> 2);
-  out[2] = (unsigned char) (((in[2] << 6) & 0xc0) | in[3]);
+  char a = __block(in[0]);
+  char b = __block(in[1]);
+  char c = __block(in[2]);
+  char d = __block(in[3]);
+
+  out[0] = (unsigned char) (a << 2 | b >> 4);
+  out[1] = (unsigned char) (b << 4 | c >> 2);
+  out[2] = (unsigned char) (((c << 6) & 0xc0) | d);
 }
 
 size_t sx_rawlen2b64len(size_t raw_length)
 {
-  return 4 * ((raw_length + 2) / 3);
+  return (size_t)(((4 * raw_length / 3) + 3) & ~3);
 }
 
 size_t sx_b64encode_in(const char *data, char *bdata, size_t data_len)
@@ -72,6 +86,7 @@ size_t sx_b64encode_in(const char *data, char *bdata, size_t data_len)
         } else ib[i] = (unsigned char)0;
       }
       encodeblock(ib, (unsigned char *)bdata + n, len);
+      break;
     }
   }