diff --git a/pkgs/additional/koreader-from-src/default.nix b/pkgs/additional/koreader-from-src/default.nix
index 9e18b945..c8d513f6 100644
--- a/pkgs/additional/koreader-from-src/default.nix
+++ b/pkgs/additional/koreader-from-src/default.nix
@@ -97,6 +97,14 @@ let
     hash = "sha256-lXjAX0BoHW3L1E54d5J+wiAlAZXVmj9Y1Un8yaCwO8w=";
   };
 
+  kobo-usbms-src-ko = fetchFromGitHub {
+    owner = "koreader";
+    repo = "KoboUSBMS";
+    name = "kobo-usbms";  # where to unpack this in `srcs`
+    rev = "v1.3.9";
+    hash = "sha256-91B0FUnmpE6TP4Lg5mj6z/U1DZQTKiPhG3ccCSgY4mQ=";
+  };
+
   leptonica-src-ko = fetchFromGitHub {
     # k2pdf needs leptonica src, because it actually patches it and builds it itself:
     # - `cp -f $(LEPTONICA_MOD)/dewarp2.c $(LEPTONICA_DIR)/src/dewarp2.c`
@@ -290,6 +298,7 @@ let
     JPEG_LIB_LINK_FLAG="-L ${lib.getLib libjpeg_turbo}/lib -l:libjpeg.so" \
     JPEG_DIR="${lib.getDev libjpeg_turbo}" \
     TURBOJPEG_LIB="${lib.getLib libjpeg_turbo}/lib/libturbojpeg.so" \
+    KOBO_USBMS_DIR="$NIX_BUILD_TOP/kobo-usbms" \
     LEPTONICA_DIR="$NIX_BUILD_TOP/leptonica" \
     LIBICONV="${lib.getLib libiconvReal}/lib/libiconv.so" \
     LIBICONV_DIR="${lib.getDev libiconvReal}" \
@@ -384,6 +393,7 @@ stdenv.mkDerivation rec {
   srcs = [
     src
     fbink-src-ko
+    kobo-usbms-src-ko
     leptonica-src-ko
     tesseract-src-ko
   ] ++ (lib.mapAttrsToList
@@ -438,7 +448,7 @@ stdenv.mkDerivation rec {
       --replace-fail '	-rm ' '	# -rm'
 
     # make some sources writable (only the `sourceRoot` is writable by default)
-    chmod -R u+w "$NIX_BUILD_TOP"/{fbink,leptonica,tesseract}
+    chmod -R u+w "$NIX_BUILD_TOP"/{fbink,kobo-usbms,leptonica,tesseract}
 
     # lots of places in Makefile.third (incorrectly) assume lib paths are relative to CURDIR,
     # so link /nix into CURDIR to allow them to work anyway
@@ -503,6 +513,7 @@ stdenv.mkDerivation rec {
     )}
 
     skip_download fbink
+    skip_download kobo-usbms
 
     # outDir should match OUTPUT_DIR in koreader-base
     outDir="$NIX_BUILD_TOP/koreader/base/build/${stdenv.hostPlatform.config}"
diff --git a/pkgs/additional/koreader-from-src/sources.nix b/pkgs/additional/koreader-from-src/sources.nix
index eee8c287..9037a535 100644
--- a/pkgs/additional/koreader-from-src/sources.nix
+++ b/pkgs/additional/koreader-from-src/sources.nix
@@ -119,12 +119,12 @@ in
     #   # package = harfbuzz;
     #   package = libAndDev harfbuzz;
     # };
-    kobo-usbms = {
-      source.url = "https://github.com/koreader/KoboUSBMS.git";
-      source.rev = "v1.3.9";
-      source.hash = "sha256-/yYpagekWlfTrXu/1DNTmBmdd3IkCDjRtslRv13mtCg=";
-      # package: not in nixpkgs
-    };
+    # kobo-usbms = {
+    #   source.url = "https://github.com/koreader/KoboUSBMS.git";
+    #   source.rev = "v1.3.9";
+    #   source.hash = "sha256-/yYpagekWlfTrXu/1DNTmBmdd3IkCDjRtslRv13mtCg=";
+    #   # package: not in nixpkgs
+    # };
     # leptonica = {
     #   source.url = "https://github.com/DanBloomberg/leptonica.git";
     #   source.rev = "1.74.1";