diff --git a/pkgs/by-name/gm/gmic-qt/package.nix b/pkgs/by-name/gm/gmic-qt/package.nix
index dec42a99a488..539b766464e6 100644
--- a/pkgs/by-name/gm/gmic-qt/package.nix
+++ b/pkgs/by-name/gm/gmic-qt/package.nix
@@ -12,6 +12,7 @@
 , libpng
 , libsForQt5
 , libtiff
+, llvmPackages
 , ninja
 , nix-update-script
 , openexr
@@ -79,7 +80,9 @@ stdenv.mkDerivation (finalAttrs: {
   ] ++ (with libsForQt5; [
     qtbase
     qttools
-  ]) ++ variants.${variant}.extraDeps;
+  ]) ++ lib.optionals stdenv.cc.isClang [
+    llvmPackages.openmp
+  ] ++ variants.${variant}.extraDeps;
 
   postPatch = ''
     patchShebangs \
diff --git a/pkgs/by-name/gm/gmic/package.nix b/pkgs/by-name/gm/gmic/package.nix
index 71402ab7e89a..38f3f8ba2261 100644
--- a/pkgs/by-name/gm/gmic/package.nix
+++ b/pkgs/by-name/gm/gmic/package.nix
@@ -13,9 +13,12 @@
 , gnused
 , graphicsmagick
 , jq
+, libX11
+, libXext
 , libjpeg
 , libpng
 , libtiff
+, llvmPackages
 , ninja
 , opencv
 , openexr
@@ -55,18 +58,24 @@ stdenv.mkDerivation (finalAttrs: {
     cimg
     fftw
     graphicsmagick
+    libX11
+    libXext
     libjpeg
     libpng
     libtiff
     opencv
     openexr
     zlib
+  ] ++ lib.optionals stdenv.cc.isClang [
+    llvmPackages.openmp
   ];
 
   cmakeFlags = [
     (lib.cmakeBool "BUILD_LIB_STATIC" false)
     (lib.cmakeBool "ENABLE_CURL" false)
     (lib.cmakeBool "ENABLE_DYNAMIC_LINKING" true)
+    (lib.cmakeBool "ENABLE_OPENCV" true)
+    (lib.cmakeBool "ENABLE_XSHM" true)
     (lib.cmakeBool "USE_SYSTEM_CIMG" true)
   ];