diff --git a/examples/render-mandoc/docs/download.1 b/examples/render-mandoc/docs/download.1
index 104f3572..acad50a9 100644
--- a/examples/render-mandoc/docs/download.1
+++ b/examples/render-mandoc/docs/download.1
@@ -14,7 +14,7 @@
 . ftr VB CB
 . ftr VBI CBI
 .\}
-.TH "download" "1" "September 2023" "Version 0.1.0" "Sample application"
+.TH "download" "1" "October 2023" "Version 0.1.0" "Sample application"
 .hy
 .SH NAME
 .PP
diff --git a/examples/render-mandoc/docs/download.md b/examples/render-mandoc/docs/download.md
index 94cae278..df151e66 100644
--- a/examples/render-mandoc/docs/download.md
+++ b/examples/render-mandoc/docs/download.md
@@ -1,6 +1,6 @@
 % download(1) Version 0.1.0 | Sample application
 % Lana Lang
-% September 2023
+% October 2023
 
 NAME
 ==================================================
diff --git a/lib/bashly.rb b/lib/bashly.rb
index 470ae2fc..9b2ec75a 100644
--- a/lib/bashly.rb
+++ b/lib/bashly.rb
@@ -15,6 +15,7 @@ module Bashly
   autoload :ConfigValidator, 'bashly/config_validator'
   autoload :Library, 'bashly/library'
   autoload :LibrarySource, 'bashly/library_source'
+  autoload :LibrarySourceConfig, 'bashly/library_source_config'
   autoload :MessageStrings, 'bashly/message_strings'
   autoload :RenderContext, 'bashly/render_context'
   autoload :RenderSource, 'bashly/render_source'
diff --git a/lib/bashly/library_source.rb b/lib/bashly/library_source.rb
index 662e8f45..1185cebf 100644
--- a/lib/bashly/library_source.rb
+++ b/lib/bashly/library_source.rb
@@ -15,7 +15,7 @@ def git?
     end
 
     def config
-      @config ||= YAML.load_file config_path
+      @config ||= LibrarySourceConfig.new(config_path).validated_data
     end
 
     def libraries
diff --git a/lib/bashly/library_source_config.rb b/lib/bashly/library_source_config.rb
new file mode 100644
index 00000000..53f381fa
--- /dev/null
+++ b/lib/bashly/library_source_config.rb
@@ -0,0 +1,48 @@
+module Bashly
+  class LibrarySourceConfig
+    include ValidationHelpers
+
+    attr_reader :path
+
+    def initialize(path)
+      @path = path
+    end
+
+    def data
+      @data ||= YAML.load_file path
+    end
+
+    def validated_data
+      validate
+      data
+    end
+
+    def validate
+      assert_root path, data
+    end
+
+  private
+
+    def assert_root(path, value)
+      assert_hash path, value
+      data.each { |id, spec| assert_lib "[#{path}] #{id}", spec }
+    end
+
+    def assert_lib(key, value)
+      assert_string "#{key}.help", value['help']
+
+      assert_optional_string "#{key}.usage", value['usage']
+      assert_optional_string "#{key}.handler", value['handler']
+      assert_optional_string "#{key}.post_install_message", value['post_install_message']
+
+      return if value['handler']
+
+      assert_array "#{key}.files", value['files'], of: :filespec
+    end
+
+    def assert_filespec(key, value)
+      assert_string "#{key}.source", value['source']
+      assert_string "#{key}.target", value['target']
+    end
+  end
+end
diff --git a/spec/approvals/examples/render-mandoc b/spec/approvals/examples/render-mandoc
index 141c88f3..c44684e0 100644
--- a/spec/approvals/examples/render-mandoc
+++ b/spec/approvals/examples/render-mandoc
@@ -44,4 +44,4 @@ ISSUE TRACKER
 AUTHORS
        Lana Lang.
 
-Version 0.1.0                   September 2023                     download(1)
+Version 0.1.0                    October 2023                      download(1)
diff --git a/spec/approvals/libraries/render/mandoc/render-1-download.1 b/spec/approvals/libraries/render/mandoc/render-1-download.1
index 08b2b76b..0c3b39c3 100644
--- a/spec/approvals/libraries/render/mandoc/render-1-download.1
+++ b/spec/approvals/libraries/render/mandoc/render-1-download.1
@@ -29,4 +29,4 @@ EXAMPLES
               download example.com ./output -f
 
 
-Version 0.1.0                   MONTH YEAR                     download(1)
+Version 0.1.0                    MONTH YEAR                      download(1)
diff --git a/spec/approvals/libraries_validation/files_array b/spec/approvals/libraries_validation/files_array
new file mode 100644
index 00000000..f78264a3
--- /dev/null
+++ b/spec/approvals/libraries_validation/files_array
@@ -0,0 +1 @@
+#<Bashly::ConfigurationError: [spec/fixtures/libraries/errors/files_array.yml] database.files must be an array>
\ No newline at end of file
diff --git a/spec/approvals/libraries_validation/files_source b/spec/approvals/libraries_validation/files_source
new file mode 100644
index 00000000..21f98c90
--- /dev/null
+++ b/spec/approvals/libraries_validation/files_source
@@ -0,0 +1 @@
+#<Bashly::ConfigurationError: [spec/fixtures/libraries/errors/files_source.yml] database.files[0].source must be a string>
\ No newline at end of file
diff --git a/spec/approvals/libraries_validation/files_target b/spec/approvals/libraries_validation/files_target
new file mode 100644
index 00000000..67580069
--- /dev/null
+++ b/spec/approvals/libraries_validation/files_target
@@ -0,0 +1 @@
+#<Bashly::ConfigurationError: [spec/fixtures/libraries/errors/files_target.yml] database.files[0].target must be a string>
\ No newline at end of file
diff --git a/spec/approvals/libraries_validation/handler_string b/spec/approvals/libraries_validation/handler_string
new file mode 100644
index 00000000..4fb9d1db
--- /dev/null
+++ b/spec/approvals/libraries_validation/handler_string
@@ -0,0 +1 @@
+#<Bashly::ConfigurationError: [spec/fixtures/libraries/errors/handler_string.yml] database.handler must be a string>
\ No newline at end of file
diff --git a/spec/approvals/libraries_validation/help_string b/spec/approvals/libraries_validation/help_string
new file mode 100644
index 00000000..8d40fb91
--- /dev/null
+++ b/spec/approvals/libraries_validation/help_string
@@ -0,0 +1 @@
+#<Bashly::ConfigurationError: [spec/fixtures/libraries/errors/help_string.yml] database.help must be a string>
\ No newline at end of file
diff --git a/spec/approvals/libraries_validation/message_string b/spec/approvals/libraries_validation/message_string
new file mode 100644
index 00000000..f9ecbea5
--- /dev/null
+++ b/spec/approvals/libraries_validation/message_string
@@ -0,0 +1 @@
+#<Bashly::ConfigurationError: [spec/fixtures/libraries/errors/message_string.yml] database.post_install_message must be a string>
\ No newline at end of file
diff --git a/spec/approvals/libraries_validation/root_hash b/spec/approvals/libraries_validation/root_hash
new file mode 100644
index 00000000..bf1c0a67
--- /dev/null
+++ b/spec/approvals/libraries_validation/root_hash
@@ -0,0 +1 @@
+#<Bashly::ConfigurationError: spec/fixtures/libraries/errors/root_hash.yml must be a hash>
\ No newline at end of file
diff --git a/spec/approvals/libraries_validation/usage_string b/spec/approvals/libraries_validation/usage_string
new file mode 100644
index 00000000..877e9c1e
--- /dev/null
+++ b/spec/approvals/libraries_validation/usage_string
@@ -0,0 +1 @@
+#<Bashly::ConfigurationError: [spec/fixtures/libraries/errors/usage_string.yml] database.usage must be a string>
\ No newline at end of file
diff --git a/spec/bashly/config_validator_spec.rb b/spec/bashly/config_validator_spec.rb
index 7e88096c..9d091fea 100644
--- a/spec/bashly/config_validator_spec.rb
+++ b/spec/bashly/config_validator_spec.rb
@@ -1,14 +1,13 @@
 describe ConfigValidator do
   fixtures = load_fixture 'script/validations'
-  subject { described_class.new options }
 
   describe '#validate' do
     fixtures.each do |fixture, options|
-      context "with :#{fixture}" do
-        let(:options) { options }
+      validator = described_class.new options
 
+      context "with :#{fixture}" do
         it 'raises an error' do
-          expect { subject.validate }.to raise_approval("validations/#{fixture}")
+          expect { validator.validate }.to raise_approval("validations/#{fixture}")
         end
       end
     end
diff --git a/spec/bashly/library_source_config_spec.rb b/spec/bashly/library_source_config_spec.rb
new file mode 100644
index 00000000..9b4739e5
--- /dev/null
+++ b/spec/bashly/library_source_config_spec.rb
@@ -0,0 +1,26 @@
+describe LibrarySourceConfig do
+  fixtures = Dir['spec/fixtures/libraries_errors/*.yml']
+  subject { described_class.new path }
+
+  let(:path) { 'spec/fixtures/libraries/libraries.yml' }
+
+  describe '#validated_data' do
+    it 'returns the data after validating it' do
+      expect(subject).to receive(:validate)
+      expect(subject.validated_data).to eq subject.data
+    end
+  end
+
+  describe '#validate' do
+    fixtures.each do |path|
+      fixture_name = File.basename path, '.yml'
+      config = described_class.new path
+
+      context "with #{fixture_name}.yml" do
+        it 'raises an error' do
+          expect { config.validate }.to raise_approval("libraries_validation/#{fixture_name}")
+        end
+      end
+    end
+  end
+end
diff --git a/spec/fixtures/libraries_validation/files_array.yml b/spec/fixtures/libraries_validation/files_array.yml
new file mode 100644
index 00000000..998fd18c
--- /dev/null
+++ b/spec/fixtures/libraries_validation/files_array.yml
@@ -0,0 +1,4 @@
+# error: files must be an array
+database:
+  help: Help text
+  files: one_file.txt
diff --git a/spec/fixtures/libraries_validation/files_source.yml b/spec/fixtures/libraries_validation/files_source.yml
new file mode 100644
index 00000000..a1532f5d
--- /dev/null
+++ b/spec/fixtures/libraries_validation/files_source.yml
@@ -0,0 +1,6 @@
+# error: files must have a source
+database:
+  help: Help text
+  files:
+    - target: some_target
+
diff --git a/spec/fixtures/libraries_validation/files_target.yml b/spec/fixtures/libraries_validation/files_target.yml
new file mode 100644
index 00000000..f690b7e9
--- /dev/null
+++ b/spec/fixtures/libraries_validation/files_target.yml
@@ -0,0 +1,6 @@
+# error: files must have a target
+database:
+  help: Help text
+  files:
+    - source: some_source
+
diff --git a/spec/fixtures/libraries_validation/handler_string.yml b/spec/fixtures/libraries_validation/handler_string.yml
new file mode 100644
index 00000000..85266e93
--- /dev/null
+++ b/spec/fixtures/libraries_validation/handler_string.yml
@@ -0,0 +1,7 @@
+# error: handler must be a string (optional)
+database:
+  help: Help text
+  handler: 1
+  files:
+    - source: "database/database.sh"
+      target: "%{user_lib_dir}/database.%{user_ext}"
diff --git a/spec/fixtures/libraries_validation/help_string.yml b/spec/fixtures/libraries_validation/help_string.yml
new file mode 100644
index 00000000..4d2ae109
--- /dev/null
+++ b/spec/fixtures/libraries_validation/help_string.yml
@@ -0,0 +1,6 @@
+# error: help must be a string
+database:
+  help: 1
+  files:
+    - source: "database/database.sh"
+      target: "%{user_lib_dir}/database.%{user_ext}"
diff --git a/spec/fixtures/libraries_validation/message_string.yml b/spec/fixtures/libraries_validation/message_string.yml
new file mode 100644
index 00000000..0ab1145d
--- /dev/null
+++ b/spec/fixtures/libraries_validation/message_string.yml
@@ -0,0 +1,7 @@
+# error: post_install_message must be a string (optional)
+database:
+  help: Help text
+  post_install_message: 1
+  files:
+    - source: "database/database.sh"
+      target: "%{user_lib_dir}/database.%{user_ext}"
diff --git a/spec/fixtures/libraries_validation/root_hash.yml b/spec/fixtures/libraries_validation/root_hash.yml
new file mode 100644
index 00000000..374aae0a
--- /dev/null
+++ b/spec/fixtures/libraries_validation/root_hash.yml
@@ -0,0 +1,6 @@
+# error: must be a hash
+- database:
+    help: Add database utilities
+    files:
+      - source: "database/database.sh"
+        target: "%{user_lib_dir}/database.%{user_ext}"
diff --git a/spec/fixtures/libraries_validation/usage_string.yml b/spec/fixtures/libraries_validation/usage_string.yml
new file mode 100644
index 00000000..8e9207e4
--- /dev/null
+++ b/spec/fixtures/libraries_validation/usage_string.yml
@@ -0,0 +1,7 @@
+# error: usage must be a string (optional)
+database:
+  help: Help text
+  usage: 1
+  files:
+    - source: "database/database.sh"
+      target: "%{user_lib_dir}/database.%{user_ext}"