diff --git a/oni/packages/emacs-config.scm b/oni/packages/emacs-config.scm
index ef69688..bfe3f4e 100644
--- a/oni/packages/emacs-config.scm
+++ b/oni/packages/emacs-config.scm
@@ -4,6 +4,7 @@
   #:use-module (guix build-system emacs)
   #:use-module ((guix licenses) #:prefix license:)
   #:use-module (gnu packages emacs-xyz)
+  #:use-module (gnu packages llvm)
   #:use-module (oni packages emacs))
 
 (define-public emacs-oni-config
@@ -148,3 +149,45 @@ Emacs")))
        ("emacs-dashboard" ,emacs-dashboard)))
     (synopsis "My core Emacs configuration")
     (description "This package provides my core configuration for Emacs")))
+
+(define-public emacs-oni-flycheck
+  (package
+   (inherit emacs-oni-config)
+   (name "emacs-oni-flycheck")
+   (arguments
+    '(#:include '("oni-flycheck.el")))
+   (propagated-inputs
+    `(("emacs-flycheck" ,emacs-flycheck)
+      ("emacs-flycheck-posframe" ,emacs-flycheck-posframe)
+      ("emacs-flycheck-cask" ,emacs-flycheck-cask)))
+   (synopsis "My Emacs flycheck configuration")
+   (description "This package provides my configuration for Emacs flycheck")))
+
+(define-public emacs-oni-lsp
+  (package
+   (inherit emacs-oni-config)
+   (name "emacs-oni-lsp")
+   (arguments
+    '(#:include '("oni-lsp.el")))
+   (propagated-inputs
+    `(("emacs-lsp-mode" ,emacs-lsp-mode)
+      ("emacs-lsp-ui" ,emacs-lsp-ui)
+      ("emacs-lsp-ivy" ,emacs-lsp-ivy)))
+   (synopsis "My Emacs LSP configuration")
+   (description "This package provides my configuration for Emacs LSP")))
+
+(define-public emacs-oni-c
+  (package
+   (inherit emacs-oni-config)
+   (name "emacs-oni-c")
+   (arguments
+    '(#:include '("oni-c.el")))
+   (propagated-inputs
+    `(("emacs-oni-flycheck" ,emacs-oni-flycheck)
+      ("emacs-oni-lsp" ,emacs-oni-lsp)
+      ("emacs-reformatter" ,emacs-reformatter)
+      ("emacs-ccls" ,emacs-ccls)
+      ;; For `clang-format'.
+      ("clang" ,clang)))
+   (synopsis "My Emacs C coding configuration")
+   (description "This package provides my configuration for coding in C")))
diff --git a/oni/packages/emacs.scm b/oni/packages/emacs.scm
index 1c871c5..4ea231a 100644
--- a/oni/packages/emacs.scm
+++ b/oni/packages/emacs.scm
@@ -100,3 +100,49 @@ custom pairs?)")
      (description "Insert Unicode char via insert-char-preview similar to insert-char command, but
 with character preview in completion prompt.")
      (license license:gpl3+))))
+
+(define-public emacs-flycheck-posframe
+  (let ((commit "8f60c9bf124ab9597d681504a73fdf116a0bde12")
+        (revision "0"))
+    (package
+     (name "emacs-flycheck-posframe")
+     (version (git-version "0.0.0" revision commit))
+     (source
+      (origin
+       (uri (git-reference
+             (url "https://github.com/alexmurray/flycheck-posframe")
+             (commit commit)))
+       (method git-fetch)
+       (file-name (git-file-name name version))
+       (sha256
+        (base32 "0qh9hzvs95jvfrspglzkwhfq6a5pinab94bbh5vzkg8jc2fq6drf"))))
+     (build-system emacs-build-system)
+     (propagated-inputs
+      `(("emacs-flycheck" ,emacs-flycheck)
+        ("emacs-posframe" ,emacs-posframe)))
+     (home-page "https://github.com/alexmurray/flycheck-posframe")
+     (synopsis "Show flycheck errors via posframe.el")
+     (description "Show flycheck errors via posframe.el")
+     (license license:gpl3+))))
+
+(define-public emacs-flycheck-cask
+  (package
+   (name "emacs-flycheck-cask")
+   (version "0.4")
+   (source
+    (origin
+     (uri (git-reference
+           (url "https://github.com/flycheck/flycheck-cask")
+           (commit version)))
+     (method git-fetch)
+     (file-name (git-file-name name version))
+     (sha256
+      (base32 "1wm5saf29gw0gp0qq5glf9qq3iras99npc2rip7bsnn0czr2mscy"))))
+   (build-system emacs-build-system)
+   (propagated-inputs
+    `(("emacs-flycheck" ,emacs-flycheck)
+      ("emacs-dash" ,emacs-dash)))
+   (home-page "https://github.com/flycheck/flycheck-cask")
+   (synopsis "Cask support for Flycheck")
+   (description "Make Flycheck use Cask packages in Cask projects.")
+   (license license:gpl3+)))