diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 5de6961a22..9d7607f000 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -7177,7 +7177,7 @@ fn (mut g Gen) or_block(var_name string, or_block ast.OrExpr, return_type ast.Ty
 	}
 	if or_block.kind == .block {
 		g.or_expr_return_type = return_type.clear_option_and_result()
-		if or_block.err_used
+		if !g.pref.skip_unused || or_block.err_used
 			|| (g.fn_decl != unsafe { nil } && (g.fn_decl.is_main || g.fn_decl.is_test)) {
 			g.writeln('\tIError err = ${cvar_name}${tmp_op}err;')
 		}
diff --git a/vlib/v/gen/c/if.v b/vlib/v/gen/c/if.v
index c5f0129346..3cd40fd2b9 100644
--- a/vlib/v/gen/c/if.v
+++ b/vlib/v/gen/c/if.v
@@ -311,7 +311,7 @@ fn (mut g Gen) if_expr(node ast.IfExpr) {
 			// define `err` for the last branch after a `if val := opt {...}' guard
 			if is_guard && guard_idx == i - 1 {
 				if err_var := branch.scope.find_var('err') {
-					if err_var.is_used {
+					if !g.pref.skip_unused || err_var.is_used {
 						cvar_name := guard_vars[guard_idx]
 						g.writeln('\tIError err = ${cvar_name}.err;')
 					}