diff --git a/spec/ruby/optional/capi/ext/set_spec.c b/spec/ruby/optional/capi/ext/set_spec.c
index 6535a11be322df..72938be1d887f0 100644
--- a/spec/ruby/optional/capi/ext/set_spec.c
+++ b/spec/ruby/optional/capi/ext/set_spec.c
@@ -1,6 +1,7 @@
 #include "ruby.h"
 #include "rubyspec.h"
 
+#ifdef RUBY_VERSION_IS_3_5
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -60,3 +61,4 @@ void Init_set_spec(void) {
 }
 #endif
 
+#endif
diff --git a/spec/ruby/optional/capi/set_spec.rb b/spec/ruby/optional/capi/set_spec.rb
index 3433014ccd46e8..3b7ee812c56ade 100644
--- a/spec/ruby/optional/capi/set_spec.rb
+++ b/spec/ruby/optional/capi/set_spec.rb
@@ -1,13 +1,13 @@
 require_relative 'spec_helper'
 
-load_extension("set")
+ruby_version_is "3.5" do
+  load_extension("set")
 
-describe "C-API Set function" do
-  before :each do
-    @s = CApiSetSpecs.new
-  end
+  describe "C-API Set function" do
+    before :each do
+      @s = CApiSetSpecs.new
+    end
 
-  ruby_version_is "3.5" do
     describe "rb_set_foreach" do
       it "calls function with each element and arg" do
         a = []