diff --git a/gcc/common/config/riscv/riscv-common.cc b/gcc/common/config/riscv/riscv-common.cc
index 1dc1d9904c7..410e673f5e0 100644
--- a/gcc/common/config/riscv/riscv-common.cc
+++ b/gcc/common/config/riscv/riscv-common.cc
@@ -401,6 +401,7 @@ static const struct riscv_ext_version riscv_ext_version_table[] =
 /* Combine extensions defined in this table  */
 static const struct riscv_ext_version riscv_combine_info[] =
 {
+  {"a", ISA_SPEC_CLASS_20191213, 2, 1},
   {"zk",  ISA_SPEC_CLASS_NONE, 1, 0},
   {"zkn",  ISA_SPEC_CLASS_NONE, 1, 0},
   {"zks",  ISA_SPEC_CLASS_NONE, 1, 0},