diff --git a/.github/workflows/binary-gems.yml b/.github/workflows/binary-gems.yml
index 4f73f0b6f..175394262 100644
--- a/.github/workflows/binary-gems.yml
+++ b/.github/workflows/binary-gems.yml
@@ -73,16 +73,28 @@ jobs:
             platform: "x64-mingw-ucrt"
             PGVERSION: 16.6-1-windows-x64
           - os: ubuntu-latest
-            ruby: "3.2"
+            ruby: "4.0"
+            platform: "x86_64-linux"
+          - os: ubuntu-latest
+            ruby: "3.0"
             platform: "x86_64-linux"
           - os: ubuntu-24.04-arm
             ruby: "4.0"
             platform: "aarch64-linux"
+          - os: ubuntu-24.04-arm
+            ruby: "3.0"
+            platform: "aarch64-linux"
           - os: macos-latest
             ruby: "4.0"
             platform: "arm64-darwin"
+          - os: macos-latest
+            ruby: "3.0"
+            platform: "arm64-darwin"
+          - os: macos-15-intel
+            ruby: "4.0"
+            platform: "x86_64-darwin"
           - os: macos-15-intel
-            ruby: "3.4"
+            ruby: "3.0"
             platform: "x86_64-darwin"
 
     runs-on: ${{ matrix.os }}
diff --git a/spec/helpers/scheduler.rb b/spec/helpers/scheduler.rb
index 73bf4de3c..1a43e7e8d 100644
--- a/spec/helpers/scheduler.rb
+++ b/spec/helpers/scheduler.rb
@@ -114,7 +114,7 @@ def scheduler_close
 		close(true)
 	end
 
-	def close(internal = false)
+	def close(internal = true)
 		# $stderr.puts [__method__, Fiber.current].inspect
 
 		unless internal
diff --git a/spec/pg/scheduler_spec.rb b/spec/pg/scheduler_spec.rb
index d7d5c7d75..408ff89ea 100644
--- a/spec/pg/scheduler_spec.rb
+++ b/spec/pg/scheduler_spec.rb
@@ -63,6 +63,7 @@
 	end
 
 	it "connects with environment variables", :postgresql_12, :unix_socket do
+		skip "requires ruby-3.2" if RUBY_VERSION < "3.2"
 		run_with_scheduler do
 			vars = PG::Connection.conninfo_parse(@conninfo_gate).each_with_object({}){|h, o| o[h[:keyword].to_sym] = h[:val] if h[:val] }
 
diff --git a/spec/pg/tuple_spec.rb b/spec/pg/tuple_spec.rb
index 12ddaf50a..5a49c042a 100644
--- a/spec/pg/tuple_spec.rb
+++ b/spec/pg/tuple_spec.rb
@@ -304,6 +304,7 @@
 	end
 
 	it "should be distributable to Ractors", :ractor do
+		skip "unstable on ruby-3.0" if RUBY_VERSION < "3.1"
 		res = @conn.exec("SELECT generate_series(1,100) AS f")
 		arr = res.ntuples.times.flat_map do |tidx1|
 			tuple = res.tuple(tidx1)