diff --git a/c/containers/mlr_dsl_ast.c b/c/containers/mlr_dsl_ast.c
index 10c3c439d..3b198cf00 100644
--- a/c/containers/mlr_dsl_ast.c
+++ b/c/containers/mlr_dsl_ast.c
@@ -183,6 +183,7 @@ char* mlr_dsl_ast_node_describe_type(mlr_dsl_ast_node_type_t type) {
 	case MD_AST_NODE_TYPE_OOSVAR_ASSIGNMENT:                return "oosvar_assignment";                break;
 	case MD_AST_NODE_TYPE_OOSVAR_FROM_FULL_SREC_ASSIGNMENT: return "oosvar_from_full_srec_assignment"; break;
 	case MD_AST_NODE_TYPE_FULL_SREC_FROM_OOSVAR_ASSIGNMENT: return "full_srec_from_oosvar_assignment"; break;
+	case MD_AST_NODE_TYPE_ENV_ASSIGNMENT:                   return "env_assignment";                   break;
 	case MD_AST_NODE_TYPE_CONTEXT_VARIABLE:                 return "context_variable";                 break;
 	case MD_AST_NODE_TYPE_STRIPPED_AWAY:                    return "stripped_away";                    break;
 	case MD_AST_NODE_TYPE_CONDITIONAL_BLOCK:                return "conditional_block";                break;
diff --git a/c/containers/mlr_dsl_ast.h b/c/containers/mlr_dsl_ast.h
index bf7c888cc..6312a14d4 100644
--- a/c/containers/mlr_dsl_ast.h
+++ b/c/containers/mlr_dsl_ast.h
@@ -34,6 +34,7 @@ typedef enum _mlr_dsl_ast_node_type_t {
 	MD_AST_NODE_TYPE_OOSVAR_ASSIGNMENT,
 	MD_AST_NODE_TYPE_OOSVAR_FROM_FULL_SREC_ASSIGNMENT,
 	MD_AST_NODE_TYPE_FULL_SREC_FROM_OOSVAR_ASSIGNMENT,
+	MD_AST_NODE_TYPE_ENV_ASSIGNMENT,
 	MD_AST_NODE_TYPE_CONTEXT_VARIABLE,
 	MD_AST_NODE_TYPE_ENV,
 	MD_AST_NODE_TYPE_STRIPPED_AWAY,
diff --git a/c/dsls/mlr_dsl_parse.y b/c/dsls/mlr_dsl_parse.y
index aeb07cdb7..4902d8f50 100644
--- a/c/dsls/mlr_dsl_parse.y
+++ b/c/dsls/mlr_dsl_parse.y
@@ -149,7 +149,7 @@ md_statement_not_braced_end(A) ::= md_srec_assignment(B).                  { A =
 md_statement_not_braced_end(A) ::= md_srec_indirect_assignment(B).         { A = B; }
 md_statement_not_braced_end(A) ::= md_oosvar_from_full_srec_assignment(B). { A = B; }
 md_statement_not_braced_end(A) ::= md_full_srec_from_oosvar_assignment(B). { A = B; }
-//md_statement_not_braced_end(A) ::= md_env_assignment(B).                   { A = B; }
+md_statement_not_braced_end(A) ::= md_env_assignment(B).                   { A = B; }
 
 // Valid in begin/end since they don't refer to srecs (although the RHSs might):
 md_statement_not_braced_end(A) ::= md_do_while_block(B).      { A = B; }
@@ -570,12 +570,9 @@ md_full_srec_from_oosvar_assignment(A)  ::= MD_TOKEN_FULL_SREC(B) MD_TOKEN_ASSIG
 	A = mlr_dsl_ast_node_alloc_binary(O->text, MD_AST_NODE_TYPE_FULL_SREC_FROM_OOSVAR_ASSIGNMENT, B, C);
 }
 
-//xxx
-//make intermediate
-
-//md_env_assignment(A)  ::= MD_TOKEN_FULL_SREC(B) MD_TOKEN_ASSIGN(O) md_oosvar_keylist(C). {
-	//A = mlr_dsl_ast_node_alloc_binary(O->text, MD_AST_NODE_TYPE_FULL_SREC_FROM_OOSVAR_ASSIGNMENT, B, C);
-//}
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_ASSIGN(O) md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary(O->text, MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B, C);
+}
 
 // ----------------------------------------------------------------
 md_srec_assignment(A)  ::= md_field_name(B) MD_TOKEN_LOGICAL_OR_EQUALS md_rhs(C). {
@@ -774,6 +771,72 @@ md_local_assignment(A)  ::= md_bound_variable(B) MD_TOKEN_POW_EQUALS md_rhs(C).
 		mlr_dsl_ast_node_alloc_binary("**", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
 }
 
+// ----------------------------------------------------------------
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_LOGICAL_OR_EQUALS md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary("=", MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B,
+		mlr_dsl_ast_node_alloc_binary("||", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
+}
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_LOGICAL_XOR_EQUALS md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary("=", MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B,
+		mlr_dsl_ast_node_alloc_binary("^^", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
+}
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_LOGICAL_AND_EQUALS md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary("=", MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B,
+		mlr_dsl_ast_node_alloc_binary("&&", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
+}
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_BITWISE_OR_EQUALS md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary("=", MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B,
+		mlr_dsl_ast_node_alloc_binary("|", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
+}
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_BITWISE_XOR_EQUALS md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary("=", MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B,
+		mlr_dsl_ast_node_alloc_binary("^", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
+}
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_BITWISE_AND_EQUALS md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary("=", MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B,
+		mlr_dsl_ast_node_alloc_binary("&", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
+}
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_BITWISE_LSH_EQUALS md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary("=", MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B,
+		mlr_dsl_ast_node_alloc_binary("<<", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
+}
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_BITWISE_RSH_EQUALS md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary("=", MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B,
+		mlr_dsl_ast_node_alloc_binary(">>", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
+}
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_PLUS_EQUALS md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary("=", MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B,
+		mlr_dsl_ast_node_alloc_binary("+", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
+}
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_MINUS_EQUALS md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary("=", MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B,
+		mlr_dsl_ast_node_alloc_binary("-", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
+}
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_DOT_EQUALS md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary("=", MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B,
+		mlr_dsl_ast_node_alloc_binary(".", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
+}
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_TIMES_EQUALS md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary("=", MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B,
+		mlr_dsl_ast_node_alloc_binary("*", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
+}
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_DIVIDE_EQUALS md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary("=", MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B,
+		mlr_dsl_ast_node_alloc_binary("/", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
+}
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_INT_DIVIDE_EQUALS md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary("=", MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B,
+		mlr_dsl_ast_node_alloc_binary("//", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
+}
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_MOD_EQUALS md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary("=", MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B,
+		mlr_dsl_ast_node_alloc_binary("%", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
+}
+md_env_assignment(A)  ::= md_env_index(B) MD_TOKEN_POW_EQUALS md_rhs(C). {
+	A = mlr_dsl_ast_node_alloc_binary("=", MD_AST_NODE_TYPE_ENV_ASSIGNMENT, B,
+		mlr_dsl_ast_node_alloc_binary("**", MD_AST_NODE_TYPE_OPERATOR, mlr_dsl_ast_tree_copy(B) , C));
+}
+
 // ----------------------------------------------------------------
 md_unset(A) ::= MD_TOKEN_UNSET(O) MD_TOKEN_ALL(B). {
 	A = mlr_dsl_ast_node_alloc_unary(O->text, MD_AST_NODE_TYPE_UNSET, B);