diff --git a/frontends/aiger/aigerparse.cc b/frontends/aiger/aigerparse.cc
index a42569301..50c2a3ce6 100644
--- a/frontends/aiger/aigerparse.cc
+++ b/frontends/aiger/aigerparse.cc
@@ -444,7 +444,7 @@ void AigerReader::parse_xaiger()
 			}
 		}
 		else if (c == 'r') {
-			uint32_t dataSize = parse_xaiger_literal(f);
+			uint32_t dataSize YS_ATTRIBUTE(unused) = parse_xaiger_literal(f);
 			flopNum = parse_xaiger_literal(f);
 			log_debug("flopNum = %u\n", flopNum);
 			log_assert(dataSize == (flopNum+1) * sizeof(uint32_t));
diff --git a/frontends/ast/simplify.cc b/frontends/ast/simplify.cc
index 2fbadcdad..743c7e18f 100644
--- a/frontends/ast/simplify.cc
+++ b/frontends/ast/simplify.cc
@@ -432,7 +432,7 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
 				while (node->simplify(true, false, false, 1, -1, false, node->type == AST_PARAMETER || node->type == AST_LOCALPARAM))
 					did_something = true;
 			if (node->type == AST_ENUM) {
-				for (auto enode : node->children){
+				for (auto enode YS_ATTRIBUTE(unused) : node->children){
 					log_assert(enode->type==AST_ENUM_ITEM);
 					while (node->simplify(true, false, false, 1, -1, false, in_param))
 						did_something = true;