diff --git a/toys/lib/toys/templates/gem_build.rb b/toys/lib/toys/templates/gem_build.rb
index c20c8eb5..509267b0 100644
--- a/toys/lib/toys/templates/gem_build.rb
+++ b/toys/lib/toys/templates/gem_build.rb
@@ -186,13 +186,16 @@ def name
       #
       def gem_name(context_dir = nil)
         return @gem_name if @gem_name
-        glob = "*.gemspec"
-        glob = ::File.join(context_dir, glob) if context_dir
-        candidates = ::Dir.glob(glob)
+        candidates =
+          if context_dir
+            Compat.glob_in_dir("*.gemspec", context_dir)
+          else
+            ::Dir.glob("*.gemspec")
+          end
         if candidates.empty?
           raise ToolDefinitionError, "Could not find a gemspec"
         end
-        candidates.first.sub(/\.gemspec$/, "")
+        ::File.basename(candidates.first, ".gemspec")
       end
 
       ##
diff --git a/toys/test/test_gem_build.rb b/toys/test/test_gem_build.rb
index 819b09d8..340606ae 100644
--- a/toys/test/test_gem_build.rb
+++ b/toys/test/test_gem_build.rb
@@ -27,6 +27,14 @@
       assert_equal("toys", template.gem_name)
     end
 
+    it "handles the gem_name field with a context dir" do
+      assert_equal("toys", template.gem_name(toys_dir))
+      template.gem_name = "toys-core"
+      assert_equal("toys-core", template.gem_name(toys_dir))
+      template.gem_name = nil
+      assert_equal("toys", template.gem_name(toys_dir))
+    end
+
     it "handles the output field" do
       assert_nil(template.output)
       template.output = "/path/to/somewhere"