diff --git a/CHANGELOG.md b/CHANGELOG.md
index 62377c7..ac95706 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,7 @@ The format is based on [Keep a Changelog], and this project adheres to [Semantic
 ### Issues Fix
 
 -  Made `Color()` constructor idempotent (previously, passing a `Color` inst silently caused a bug)
+-  Fixed unable to override/customize spec (#359)
 
 ## [v1.1.0] - 23 July 2024
 
diff --git a/test/github-theme/config/overrides_spec.lua b/test/github-theme/config/overrides_spec.lua
index d9b7fb7..8b7df93 100644
--- a/test/github-theme/config/overrides_spec.lua
+++ b/test/github-theme/config/overrides_spec.lua
@@ -23,6 +23,7 @@ describe('config > groups', function()
         all = { Normal = { fg = '#123456', bg = '#654321' } },
       },
     })
+
     vim.cmd.colorscheme({ args = { 'github_dark_dimmed' } })
     assert.same({}, t_util.get_hl('Normal'))
   end)
@@ -30,10 +31,11 @@ describe('config > groups', function()
   it('clearing group combines properly with more-specific overrides', function()
     require('github-theme').setup({
       groups = {
-        all = { Normal = {} },
         github_dark_dimmed = { Normal = { fg = '#123456', bg = '#654321' } },
+        all = { Normal = {} },
       },
     })
+
     vim.cmd.colorscheme({ args = { 'github_dark_dimmed' } })
     assert.same(
       { fg = tonumber('123456', 16), bg = tonumber('654321', 16) },
@@ -45,6 +47,7 @@ describe('config > groups', function()
     require('github-theme').setup({
       groups = { all = { Normal = { fg = '#123456', bg = '#654321' } } },
     })
+
     vim.cmd.colorscheme({ args = { 'github_dark_dimmed' } })
     assert.same(
       { fg = tonumber('123456', 16), bg = tonumber('654321', 16) },
@@ -55,10 +58,11 @@ describe('config > groups', function()
   it('overriding group combines properly with more-specific overrides (1)', function()
     require('github-theme').setup({
       groups = {
-        all = { Normal = { link = 'NormalNC' } },
         github_dark_dimmed = { Normal = { fg = '#123456', bg = '#654321' } },
+        all = { Normal = { link = 'NormalNC' } },
       },
     })
+
     vim.cmd.colorscheme({ args = { 'github_dark_dimmed' } })
     assert.is_nil(t_util.get_hl('Normal', true).link)
   end)
@@ -66,10 +70,11 @@ describe('config > groups', function()
   it('overriding group combines properly with more-specific overrides (2)', function()
     require('github-theme').setup({
       groups = {
-        all = { Normal = { fg = '#123456', bg = '#654321' } },
         github_dark_dimmed = { Normal = { link = 'NormalNC' } },
+        all = { Normal = { fg = '#123456', bg = '#654321' } },
       },
     })
+
     vim.cmd.colorscheme({ args = { 'github_dark_dimmed' } })
     assert.same({ link = 'NormalNC' }, t_util.get_hl('Normal', true))
   end)
@@ -78,6 +83,7 @@ describe('config > groups', function()
     require('github-theme').setup({
       groups = { all = { Normal = { link = 'NormalNC' } } },
     })
+
     vim.cmd.colorscheme({ args = { 'github_dark_dimmed' } })
     assert.same({ link = 'NormalNC' }, t_util.get_hl('Normal', true))
   end)
@@ -106,3 +112,25 @@ describe('config > groups', function()
     )
   end)
 end)
+
+describe('config > specs', function()
+  before_each(function()
+    require('github-theme.util.reload')(true)
+  end)
+
+  it('should allow overriding the spec', function()
+    require('github-theme').setup({
+      specs = {
+        github_dark_dimmed = { bg1 = '#654321' },
+        github_dark = { bg1 = '#652322' },
+        all = { bg1 = '#123456' },
+      },
+    })
+
+    local spec = require('github-theme.spec').load('github_dark_dimmed')
+    assert.equals('#654321', spec.bg1)
+
+    vim.cmd.colorscheme({ args = { 'github_dark_dimmed' } })
+    assert.same(tonumber('654321', 16), t_util.get_hl('Normal').bg)
+  end)
+end)