diff --git a/lib/solargraph/library.rb b/lib/solargraph/library.rb
index dff701cb..4dd9b9ba 100644
--- a/lib/solargraph/library.rb
+++ b/lib/solargraph/library.rb
@@ -267,10 +267,15 @@ def locate_ref location
       return if map.nil?
       pin = map.requires.select { |p| p.location.range.contain?(location.range.start) }.first
       return nil if pin.nil?
+      return_if_match = proc do |full|
+        if source_map_hash.key?(full)
+          return Location.new(full, Solargraph::Range.from_to(0, 0, 0, 0))
+        end
+      end
       workspace.require_paths.each do |path|
-        full = Pathname.new(path).join("#{pin.name}.rb").to_s
-        next unless source_map_hash.key?(full)
-        return Location.new(full, Solargraph::Range.from_to(0, 0, 0, 0))
+        full = File.join path, pin.name
+        return_if_match.(full)
+        return_if_match.(full << ".rb")
       end
       nil
     rescue FileNotFoundError
@@ -481,10 +486,12 @@ def source_map_external_require_hash
     def find_external_requires source_map
       new_set = source_map.requires.map(&:name).to_set
       # return if new_set == source_map_external_require_hash[source_map.filename]
+      _filenames = nil
+      filenames = ->{ _filenames ||= workspace.filenames.to_set }
       source_map_external_require_hash[source_map.filename] = new_set.reject do |path|
         workspace.require_paths.any? do |base|
-          full = Pathname.new(base).join("#{path}.rb").to_s
-          workspace.filenames.include?(full)
+          full = File.join(base, path)
+          filenames[].include?(full) or filenames[].include?(full << ".rb")
         end
       end
       @external_requires = nil
diff --git a/lib/solargraph/workspace.rb b/lib/solargraph/workspace.rb
index 7efadf6f..c8ab2ed4 100644
--- a/lib/solargraph/workspace.rb
+++ b/lib/solargraph/workspace.rb
@@ -104,7 +104,8 @@ def source filename
     # @return [Boolean]
     def would_require? path
       require_paths.each do |rp|
-        return true if File.exist?(File.join(rp, "#{path}.rb"))
+        full = File.join rp, path
+        return true if File.exist?(full) or File.exist?(full << ".rb")
       end
       false
     end
diff --git a/lib/solargraph/yard_map.rb b/lib/solargraph/yard_map.rb
index 89208a2b..6b118764 100755
--- a/lib/solargraph/yard_map.rb
+++ b/lib/solargraph/yard_map.rb
@@ -120,8 +120,9 @@ def require_reference path
       # @type [Gem::Specification]
       spec = spec_for_require(path)
       spec.full_require_paths.each do |rp|
-        file = File.join(rp, "#{path}.rb")
-        next unless File.file?(file)
+        file = File.join(rp, path)
+        file = [file, file + ".rb"].find { |file| File.file?(file) }
+        next unless file
         return Solargraph::Location.new(file, Solargraph::Range.from_to(0, 0, 0, 0))
       end
       nil