diff --git a/pkgs/ruby/spec/lib/kernaux/snprintf1_spec.rb b/pkgs/ruby/spec/lib/kernaux/snprintf1_spec.rb
index bbf687d..439b888 100644
--- a/pkgs/ruby/spec/lib/kernaux/snprintf1_spec.rb
+++ b/pkgs/ruby/spec/lib/kernaux/snprintf1_spec.rb
@@ -42,7 +42,7 @@ RSpec.describe KernAux, '.snprintf1' do
     end
 
     context 'when format is too long' do
-      let(:format) { "%s#{' ' * 98}" }
+      let(:format) { "%s#{' ' * 99}" }
 
       specify do
         expect { snprintf1 }.to raise_error ArgumentError, 'invalid format'
@@ -96,7 +96,7 @@ RSpec.describe KernAux, '.snprintf1' do
     end
 
     context 'when format is too long' do
-      let(:format) { "%s#{' ' * 98}" }
+      let(:format) { "%s#{' ' * 99}" }
 
       specify do
         expect { snprintf1 }.to raise_error ArgumentError, 'invalid format'