1 files changed, 10 insertions, 2 deletions
diff --git a/lib/rubygems/specification.rb b/lib/rubygems/specification.rb
index 4c4564e155..ea3e3ecf2b 100644
--- a/lib/rubygems/specification.rb
+++ b/lib/rubygems/specification.rb
@@ -108,6 +108,8 @@ class Gem::Specification < Gem::BasicSpecification
 
   private_constant :LOAD_CACHE if defined? private_constant
 
+  VALID_NAME_PATTERN = /\A[a-zA-Z0-9\.\-\_]+\z/ # :nodoc:
+
   # :startdoc:
 
   ##
@@ -2672,9 +2674,15 @@ class Gem::Specification < Gem::BasicSpecification
       end
     end
 
-    unless String === name then
+    if !name.is_a?(String) then
+      raise Gem::InvalidSpecificationException,
+            "invalid value for attribute name: \"#{name.inspect}\" must be a string"
+    elsif name !~ /[a-zA-Z]/ then
+      raise Gem::InvalidSpecificationException,
+            "invalid value for attribute name: #{name.dump} must include at least one letter"
+    elsif name !~ VALID_NAME_PATTERN then
       raise Gem::InvalidSpecificationException,
-            "invalid value for attribute name: \"#{name.inspect}\""
+            "invalid value for attribute name: #{name.dump} can only include letters, numbers, dashes, and underscores"
     end
 
     if raw_require_paths.empty? then