diff --git a/flake.lock b/flake.lock
index 3fc2fe6b4..3e80c3957 100644
--- a/flake.lock
+++ b/flake.lock
@@ -36,10 +36,30 @@
       "inputs": {
         "mozilla-overlay": "mozilla-overlay",
         "nixpkgs": "nixpkgs",
+        "sipyco": "sipyco",
         "src-migen": "src-migen",
         "src-misoc": "src-misoc",
-        "src-pythonparser": "src-pythonparser",
-        "src-sipyco": "src-sipyco"
+        "src-pythonparser": "src-pythonparser"
+      }
+    },
+    "sipyco": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1644634510,
+        "narHash": "sha256-5p88NKK/DTdb0F0+/7uObBohthdxHWLl782AaiPRf8E=",
+        "owner": "m-labs",
+        "repo": "sipyco",
+        "rev": "e9e69527927761544ab6d62f751e1ff512d1e661",
+        "type": "github"
+      },
+      "original": {
+        "owner": "m-labs",
+        "repo": "sipyco",
+        "type": "github"
       }
     },
     "src-migen": {
@@ -91,22 +111,6 @@
         "repo": "pythonparser",
         "type": "github"
       }
-    },
-    "src-sipyco": {
-      "flake": false,
-      "locked": {
-        "lastModified": 1641866796,
-        "narHash": "sha256-TSH0IgNbi9IcMcBDb2nWRphKlxstbWeATjrGbi6K2m0=",
-        "owner": "m-labs",
-        "repo": "sipyco",
-        "rev": "b04234c49379cd446d4cb3346d4741868d86841a",
-        "type": "github"
-      },
-      "original": {
-        "owner": "m-labs",
-        "repo": "sipyco",
-        "type": "github"
-      }
     }
   },
   "root": "root",
diff --git a/flake.nix b/flake.nix
index 3c6a1ae7e..dcea33514 100644
--- a/flake.nix
+++ b/flake.nix
@@ -3,13 +3,14 @@
 
   inputs.nixpkgs.url = github:NixOS/nixpkgs/nixos-21.11;
   inputs.mozilla-overlay = { url = github:mozilla/nixpkgs-mozilla; flake = false; };
-  inputs.src-sipyco = { url = github:m-labs/sipyco; flake = false; };
+  inputs.sipyco.url = github:m-labs/sipyco;
+  inputs.sipyco.inputs.nixpkgs.follows = "nixpkgs";
   inputs.src-pythonparser = { url = github:m-labs/pythonparser; flake = false; };
 
   inputs.src-migen = { url = github:m-labs/migen; flake = false; };
   inputs.src-misoc = { type = "git"; url = "https://github.com/m-labs/misoc.git"; submodules = true; flake = false; };
 
-  outputs = { self, nixpkgs, mozilla-overlay, src-sipyco, src-pythonparser, src-migen, src-misoc }:
+  outputs = { self, nixpkgs, mozilla-overlay, sipyco, src-pythonparser, src-migen, src-misoc }:
     let
       pkgs = import nixpkgs { system = "x86_64-linux"; overlays = [ (import mozilla-overlay) ]; };
 
@@ -53,12 +54,6 @@
         fontconfig
       ];
 
-      sipyco = pkgs.python3Packages.buildPythonPackage {
-        name = "sipyco";
-        src = src-sipyco;
-        propagatedBuildInputs = with pkgs.python3Packages; [ pybase64 numpy ];
-      };
-
       pythonparser = pkgs.python3Packages.buildPythonPackage {
         name = "pythonparser";
         src = src-pythonparser;
@@ -157,7 +152,7 @@
 
         nativeBuildInputs = [ pkgs.qt5.wrapQtAppsHook ];
         # keep llvm_x and lld_x in sync with llvmlite
-        propagatedBuildInputs = [ pkgs.llvm_11 pkgs.lld_11 llvmlite-new sipyco pythonparser ]
+        propagatedBuildInputs = [ pkgs.llvm_11 pkgs.lld_11 llvmlite-new sipyco.packages.x86_64-linux.sipyco pythonparser ]
           ++ (with pkgs.python3Packages; [ pyqtgraph pygit2 numpy dateutil scipy prettytable pyserial python-Levenshtein h5py pyqt5 qasync ]);
 
         dontWrapQtApps = true;
@@ -372,7 +367,7 @@
       };
     in rec {
       packages.x86_64-linux = {
-        inherit sipyco pythonparser qasync openocd-bscanspi artiq;
+        inherit pythonparser qasync openocd-bscanspi artiq;
         inherit migen misoc asyncserial microscope vivadoEnv vivado;
         artiq-board-kc705-nist_clock = makeArtiqBoardPackage {
           target = "kc705";