diff --git a/CHANGELOG.md b/CHANGELOG.md
index d7e5af83..27b3952a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@ Breaking changes:
 New features:
 
 Bugfixes:
+- Fixed `Semigroup.append` broken for `Array` (#4 by @Renegatto)
 
 Other improvements:
 
diff --git a/src/Data/Semigroup.lua b/src/Data/Semigroup.lua
index 22165467..6949b09a 100644
--- a/src/Data/Semigroup.lua
+++ b/src/Data/Semigroup.lua
@@ -4,7 +4,15 @@ return {
     return function(ys)
       if #xs == 0 then return ys end
       if #ys == 0 then return xs end
-      return table.concat(xs, ys)
+      local result = {}
+      for index, value in ipairs(xs) do
+        result[index] = value
+      end
+      local offset = #result
+      for index, value in ipairs(ys) do
+        result[index + offset] = value
+      end
+      return result
     end
   end)
 }