diff --git a/lib/rubygems/specification_policy.rb b/lib/rubygems/specification_policy.rb
index da3beee628..057c6ccb9e 100644
--- a/lib/rubygems/specification_policy.rb
+++ b/lib/rubygems/specification_policy.rb
@@ -343,7 +343,7 @@ duplicate dependency on #{dep}, (#{prev.requirement}) use:
               String
     end
 
-    unless Array === val && val.all? {|x| x.is_a?(klass) }
+    unless Array === val && val.all? {|x| x.is_a?(klass) || (field == :licenses && x.nil?) }
       error "#{field} must be an Array of #{klass}"
     end
   end
@@ -358,6 +358,8 @@ duplicate dependency on #{dep}, (#{prev.requirement}) use:
     licenses = @specification.licenses
 
     licenses.each do |license|
+      next if license.nil?
+
       if license.length > 64
         error "each license must be 64 characters or less"
       end
@@ -368,11 +370,12 @@ duplicate dependency on #{dep}, (#{prev.requirement}) use:
     licenses = @specification.licenses
 
     licenses.each do |license|
-      next if Gem::Licenses.match?(license)
+      next if Gem::Licenses.match?(license) || license.nil?
       suggestions = Gem::Licenses.suggestions(license)
       message = <<-WARNING
 license value '#{license}' is invalid.  Use a license identifier from
-http://spdx.org/licenses or '#{Gem::Licenses::NONSTANDARD}' for a nonstandard license.
+http://spdx.org/licenses or '#{Gem::Licenses::NONSTANDARD}' for a nonstandard license,
+or set it to nil if you don't want to specify a license.
       WARNING
       message += "Did you mean #{suggestions.map {|s| "'#{s}'" }.join(", ")}?\n" unless suggestions.nil?
       warning(message)
@@ -380,7 +383,8 @@ http://spdx.org/licenses or '#{Gem::Licenses::NONSTANDARD}' for a nonstandard li
 
     warning <<-WARNING if licenses.empty?
 licenses is empty, but is recommended.  Use a license identifier from
-http://spdx.org/licenses or '#{Gem::Licenses::NONSTANDARD}' for a nonstandard license.
+http://spdx.org/licenses or '#{Gem::Licenses::NONSTANDARD}' for a nonstandard license,
+or set it to nil if you don't want to specify a license.
     WARNING
   end
 
diff --git a/test/rubygems/test_gem_commands_build_command.rb b/test/rubygems/test_gem_commands_build_command.rb
index 42f09003fc..42715df8ea 100644
--- a/test/rubygems/test_gem_commands_build_command.rb
+++ b/test/rubygems/test_gem_commands_build_command.rb
@@ -199,7 +199,8 @@ class TestGemCommandsBuildCommand < Gem::TestCase
 
     error = @ui.error.split "\n"
     assert_equal "WARNING:  licenses is empty, but is recommended.  Use a license identifier from", error.shift
-    assert_equal "http://spdx.org/licenses or 'Nonstandard' for a nonstandard license.", error.shift
+    assert_equal "http://spdx.org/licenses or 'Nonstandard' for a nonstandard license,", error.shift
+    assert_equal "or set it to nil if you don't want to specify a license.", error.shift
     assert_equal "WARNING:  See https://guides.rubygems.org/specification-reference/ for help", error.shift
     assert_equal [], error
 
diff --git a/test/rubygems/test_gem_specification.rb b/test/rubygems/test_gem_specification.rb
index 6a893f09c9..9e68c40b7c 100644
--- a/test/rubygems/test_gem_specification.rb
+++ b/test/rubygems/test_gem_specification.rb
@@ -3086,10 +3086,22 @@ Please report a bug if this causes problems.
 
     assert_match <<-WARNING, @ui.error
 WARNING:  licenses is empty, but is recommended.  Use a license identifier from
-http://spdx.org/licenses or 'Nonstandard' for a nonstandard license.
+http://spdx.org/licenses or 'Nonstandard' for a nonstandard license,
+or set it to nil if you don't want to specify a license.
     WARNING
   end
 
+  def test_validate_nil_license
+    util_setup_validate
+
+    use_ui @ui do
+      @a1.license = nil
+      @a1.validate
+    end
+
+    assert_empty @ui.error
+  end
+
   def test_validate_license_in_a_non_packaging_context
     util_setup_validate
 
@@ -3126,7 +3138,8 @@ http://spdx.org/licenses or 'Nonstandard' for a nonstandard license.
 
     assert_match <<-WARNING, @ui.error
 WARNING:  license value 'BSD' is invalid.  Use a license identifier from
-http://spdx.org/licenses or 'Nonstandard' for a nonstandard license.
+http://spdx.org/licenses or 'Nonstandard' for a nonstandard license,
+or set it to nil if you don't want to specify a license.
     WARNING
   end
 
@@ -3184,11 +3197,13 @@ http://spdx.org/licenses or 'Nonstandard' for a nonstandard license.
 
     assert_match <<-WARNING, @ui.error
 WARNING:  license value 'GPL-2.0+ FOO' is invalid.  Use a license identifier from
-http://spdx.org/licenses or 'Nonstandard' for a nonstandard license.
+http://spdx.org/licenses or 'Nonstandard' for a nonstandard license,
+or set it to nil if you don't want to specify a license.
     WARNING
     assert_match <<-WARNING, @ui.error
 WARNING:  license value 'GPL-2.0 FOO' is invalid.  Use a license identifier from
-http://spdx.org/licenses or 'Nonstandard' for a nonstandard license.
+http://spdx.org/licenses or 'Nonstandard' for a nonstandard license,
+or set it to nil if you don't want to specify a license.
     WARNING
   end
 
@@ -3202,7 +3217,8 @@ http://spdx.org/licenses or 'Nonstandard' for a nonstandard license.
 
     assert_match <<-WARNING, @ui.error
 WARNING:  license value 'GPL-2.0+ WITH Autocofn-exception-2.0' is invalid.  Use a license identifier from
-http://spdx.org/licenses or 'Nonstandard' for a nonstandard license.
+http://spdx.org/licenses or 'Nonstandard' for a nonstandard license,
+or set it to nil if you don't want to specify a license.
     WARNING
   end
 
@@ -3216,7 +3232,8 @@ http://spdx.org/licenses or 'Nonstandard' for a nonstandard license.
 
     assert_match <<-WARNING, @ui.error
 WARNING:  license value 'ruby' is invalid.  Use a license identifier from
-http://spdx.org/licenses or 'Nonstandard' for a nonstandard license.
+http://spdx.org/licenses or 'Nonstandard' for a nonstandard license,
+or set it to nil if you don't want to specify a license.
 Did you mean 'Ruby'?
     WARNING
   end