diff --git a/gas/config/tc-riscv.c b/gas/config/tc-riscv.c
index 993161568f..99b007f59f 100644
--- a/gas/config/tc-riscv.c
+++ b/gas/config/tc-riscv.c
@@ -586,6 +586,7 @@ validate_riscv_insn (const struct riscv_opcode *opc, int length)
 	  case 'v': used_bits |= ENCODE_RVC_IMM (-1U); break;
 	  case 'w': break; /* RS1S, constrained to equal RD */
 	  case 'x': break; /* RS2S, constrained to equal RD */
+	  case 'z': break; /* RS2S, contrained to be x0 */
 	  case 'K': used_bits |= ENCODE_RVC_ADDI4SPN_IMM (-1U); break;
 	  case 'L': used_bits |= ENCODE_RVC_ADDI16SP_IMM (-1U); break;
 	  case 'M': used_bits |= ENCODE_RVC_SWSP_IMM (-1U); break;
@@ -1472,6 +1473,11 @@ riscv_ip (char *str, struct riscv_cl_insn *ip, expressionS *imm_expr,
 		      || regno != X_SP)
 		    break;
 		  continue;
+		case 'z': /* RS2, contrained to equal x0.  */
+		  if (!reg_lookup (&s, RCLASS_GPR, &regno)
+		      || regno != 0)
+		    break;
+		  continue;
 		case '>':
 		  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
 		      || imm_expr->X_op != O_constant
diff --git a/opcodes/riscv-opc.c b/opcodes/riscv-opc.c
index 72e6b9d48f..bd652590b5 100644
--- a/opcodes/riscv-opc.c
+++ b/opcodes/riscv-opc.c
@@ -247,6 +247,7 @@ const struct riscv_opcode riscv_opcodes[] =
 {"and",         0, {"I", 0},   "d,s,j",  MATCH_ANDI, MASK_ANDI, match_opcode, INSN_ALIAS },
 {"beqz",        0, {"C", 0},   "Cs,Cp",  MATCH_C_BEQZ, MASK_C_BEQZ, match_opcode, INSN_ALIAS|INSN_CONDBRANCH },
 {"beqz",        0, {"I", 0},   "s,p",  MATCH_BEQ, MASK_BEQ | MASK_RS2, match_opcode, INSN_ALIAS|INSN_CONDBRANCH },
+{"beq",         0, {"C", 0},   "Cs,Cz,Cp",  MATCH_C_BEQZ, MASK_C_BEQZ, match_opcode, INSN_ALIAS|INSN_CONDBRANCH },
 {"beq",         0, {"I", 0},   "s,t,p",  MATCH_BEQ, MASK_BEQ, match_opcode, INSN_CONDBRANCH },
 {"blez",        0, {"I", 0},   "t,p",  MATCH_BGE, MASK_BGE | MASK_RS1, match_opcode, INSN_ALIAS|INSN_CONDBRANCH },
 {"bgez",        0, {"I", 0},   "s,p",  MATCH_BGE, MASK_BGE | MASK_RS2, match_opcode, INSN_ALIAS|INSN_CONDBRANCH },
@@ -262,6 +263,7 @@ const struct riscv_opcode riscv_opcodes[] =
 {"bgtu",        0, {"I", 0},   "t,s,p",  MATCH_BLTU, MASK_BLTU, match_opcode, INSN_ALIAS|INSN_CONDBRANCH },
 {"bnez",        0, {"C", 0},   "Cs,Cp",  MATCH_C_BNEZ, MASK_C_BNEZ, match_opcode, INSN_ALIAS|INSN_CONDBRANCH },
 {"bnez",        0, {"I", 0},   "s,p",  MATCH_BNE, MASK_BNE | MASK_RS2, match_opcode, INSN_ALIAS|INSN_CONDBRANCH },
+{"bne",         0, {"C", 0},   "Cs,Cz,Cp",  MATCH_C_BNEZ, MASK_C_BNEZ, match_opcode, INSN_ALIAS|INSN_CONDBRANCH },
 {"bne",         0, {"I", 0},   "s,t,p",  MATCH_BNE, MASK_BNE, match_opcode, INSN_CONDBRANCH },
 {"addi",        0, {"C", 0},   "Ct,Cc,CK", MATCH_C_ADDI4SPN, MASK_C_ADDI4SPN, match_c_addi4spn, INSN_ALIAS },
 {"addi",        0, {"C", 0},   "d,CU,Cj",  MATCH_C_ADDI, MASK_C_ADDI, match_rd_nonzero, INSN_ALIAS },