diff --git a/dlls/secur32/base64_codec.c b/dlls/secur32/base64_codec.c
index 4aab8380550..d09b24d5f88 100644
--- a/dlls/secur32/base64_codec.c
+++ b/dlls/secur32/base64_codec.c
@@ -72,7 +72,7 @@ SECURITY_STATUS encodeBase64(PBYTE in_buf, int in_len, char* out_buf,
             out_buf[i + 1] = b64[ ((d[0] << 4) & 0x30) | (d[1] >> 4 & 0x0f)];
             /* third char is the last 4 bits of the second byte padded with
              * two zeroes */
-            out_buf[i + 2] = b64[ ((d[1] >> 4) & 0x3c) ];
+            out_buf[i + 2] = b64[ ((d[1] << 2) & 0x3c) ];
             /* fourth char is a = to indicate one byte of padding */
             out_buf[i + 3] = '=';
             out_buf[i + 4] = 0;