diff --git a/library/RLCMAC_EncDec.cc b/library/RLCMAC_EncDec.cc
index 4dba35a..ea93de4 100644
--- a/library/RLCMAC_EncDec.cc
+++ b/library/RLCMAC_EncDec.cc
@@ -438,6 +438,28 @@
 	dst_ttcn_buffer.increase_length(length_bytes);
 }
 
+/* Append padding bytes and spare bits at the end of ttcn_buffer, based on requested CS */
+static void encode_trailing_padding_spb(TTCN_Buffer& ttcn_buffer, CodingScheme cs)
+{
+	uint8_t buf[256]; /* enough to fit any RLCMAC buffer*/
+	uint32_t blk_len = RLCMAC__Templates::f__rlcmac__cs__mcs2block__len(cs);
+	uint32_t blk_len_no_spb = RLCMAC__Templates::f__rlcmac__cs__mcs2block__len__no__spare__bits(cs);
+	uint32_t data_len = ttcn_buffer.get_len();
+
+	if (data_len > blk_len_no_spb) {
+		fprintf(stderr, "Buffer too large for requested CS! %s (%s:%u)\n", __func__, __FILE__, __LINE__);
+		// TODO: throw exception?
+	}
+
+	for (int i = 0; i < blk_len_no_spb - data_len; i++)
+		buf[i] = 0x2b; /* Padding bits if needed */
+	for (int i = blk_len_no_spb - data_len; i < blk_len - data_len; i++)
+		buf[i] = 0x00;  /* Spare bits if needed */
+
+	const OCTETSTRING& pad_octstr = OCTETSTRING(blk_len - data_len, buf);
+	ttcn_buffer.put_string(pad_octstr);
+}
+
 /////////////////////
 // DECODE
 /////////////////////
@@ -970,6 +992,8 @@
 		}
 	}
 
+	encode_trailing_padding_spb(ttcn_buffer, in.cs());
+
 	ttcn_buffer.get_string(ret_val);
 	return ret_val;
 }
@@ -1040,6 +1064,8 @@
 		}
 	}
 
+	encode_trailing_padding_spb(ttcn_buffer, in.mcs());
+
 	ttcn_buffer.get_string(ret_val);
 	return ret_val;
 }
@@ -1133,6 +1159,8 @@
 		}
 	}
 
+	encode_trailing_padding_spb(ttcn_buffer, in.cs());
+
 	ttcn_buffer.get_string(ret_val);
 	return ret_val;
 }
@@ -1320,6 +1348,8 @@
 	put_egprs_data_block(aligned_buffer, data_block_offsets[0], data_block_bits, ttcn_buffer);
 	//printbuffer("after merging data block", ttcn_buffer);
 
+	encode_trailing_padding_spb(ttcn_buffer, in.mcs());
+
 	ttcn_buffer.get_string(ret_val);
 	return ret_val;
 }