diff --git a/README.md b/README.md
index 80a2650..3ffbc38 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ Typst, Markdown, etc.)—diagnostics included.
 
 - Async compilation via `vim.system()`
 - Built-in presets for Typst, LaTeX (latexmk, pdflatex, tectonic), Markdown,
-  GitHub-flavored Markdown, AsciiDoc, PlantUML, Mermaid, and Quarto
+  GitHub-flavored Markdown, AsciiDoc, and Quarto
 - Compiler errors via `vim.diagnostic` or quickfix
 - Previewer auto-close on buffer deletion
 
diff --git a/doc/preview.txt b/doc/preview.txt
index 383a8f5..0e54a62 100644
--- a/doc/preview.txt
+++ b/doc/preview.txt
@@ -11,7 +11,7 @@ in Neovim. It provides a unified interface for any compilation workflow —
 LaTeX, Typst, Markdown, or anything else with a CLI compiler.
 
 The plugin ships with opt-in presets for common tools (Typst, LaTeX, Pandoc,
-AsciiDoc, PlantUML, Mermaid, Quarto) and supports fully custom providers.
+AsciiDoc, Quarto) and supports fully custom providers.
 See |preview-presets|.
 
 ==============================================================================
@@ -180,8 +180,6 @@ override individual fields by passing a table instead: >lua
   `markdown`           pandoc → HTML (standalone, embedded)
   `github`             pandoc → HTML (GitHub-styled, `-f gfm` input)
   `asciidoctor`        asciidoctor → HTML (AsciiDoc with SSE reload)
-  `plantuml`           plantuml → SVG (UML diagrams, `.puml`)
-  `mermaid`            mmdc → SVG (Mermaid diagrams, `.mmd`)
   `quarto`             quarto render → HTML (scientific publishing)
 
 ==============================================================================
diff --git a/flake.nix b/flake.nix
index f6c279b..d5bdae4 100644
--- a/flake.nix
+++ b/flake.nix
@@ -19,10 +19,9 @@
     {
       formatter = forEachSystem (pkgs: pkgs.nixfmt-tree);
 
-      devShells = forEachSystem (
-        pkgs:
-        let
-          devTools = [
+      devShells = forEachSystem (pkgs: {
+        default = pkgs.mkShell {
+          packages = [
             (pkgs.luajit.withPackages (
               ps: with ps; [
                 busted
@@ -33,25 +32,10 @@
             pkgs.stylua
             pkgs.selene
             pkgs.lua-language-server
+            pkgs.plantuml
+            pkgs.mermaid-cli
           ];
-        in
-        {
-          default = pkgs.mkShell {
-            packages = devTools;
-          };
-          presets = pkgs.mkShell {
-            packages = devTools ++ [
-              pkgs.typst
-              pkgs.texliveMedium
-              pkgs.tectonic
-              pkgs.pandoc
-              pkgs.asciidoctor
-              pkgs.quarto
-              pkgs.plantuml
-              pkgs.mermaid-cli
-            ];
-          };
-        }
-      );
+        };
+      });
     };
 }
diff --git a/lua/preview/presets.lua b/lua/preview/presets.lua
index d4b03cc..1b5333e 100644
--- a/lua/preview/presets.lua
+++ b/lua/preview/presets.lua
@@ -115,24 +115,6 @@ local function parse_asciidoctor(output)
   return diagnostics
 end
 
----@param output string
----@return preview.Diagnostic[]
-local function parse_mermaid(output)
-  local lnum = output:match('Parse error on line (%d+)')
-  if not lnum then
-    return {}
-  end
-  local msg = output:match('(Expecting .+)') or 'parse error'
-  return {
-    {
-      lnum = tonumber(lnum) - 1,
-      col = 0,
-      message = msg,
-      severity = vim.diagnostic.severity.ERROR,
-    },
-  }
-end
-
 ---@type preview.ProviderConfig
 M.typst = {
   ft = 'typst',
@@ -331,7 +313,19 @@ M.mermaid = {
     return (ctx.file:gsub('%.mmd$', '.svg'))
   end,
   error_parser = function(output)
-    return parse_mermaid(output)
+    local diagnostics = {}
+    for line in output:gmatch('[^\r\n]+') do
+      local lnum = line:match('^%s*Parse error on line (%d+)')
+      if lnum then
+        table.insert(diagnostics, {
+          lnum = tonumber(lnum) - 1,
+          col = 0,
+          message = line,
+          severity = vim.diagnostic.severity.ERROR,
+        })
+      end
+    end
+    return diagnostics
   end,
   clean = function(ctx)
     return { 'rm', '-f', (ctx.file:gsub('%.mmd$', '.svg')) }