diff --git a/pkgs/nim-packages/generic.nix b/pkgs/nim-packages/generic.nix
index c658e05..14f8c9b 100644
--- a/pkgs/nim-packages/generic.nix
+++ b/pkgs/nim-packages/generic.nix
@@ -10,10 +10,29 @@ let
     optionals (deps != []) ((getInputsFn (head deps)) ++
                             (getRecursiveInputs getInputsFn (head deps).nimDeps) ++
                             (getRecursiveInputs getInputsFn (tail deps)));
+
   rNativeBuildInputs =
     nativeBuildInputs ++ (getRecursiveInputs (i: i.nativeBuildInputs) nimDeps);
+
   rBuildInputs =
     buildInputs ++ (getRecursiveInputs (i: i.buildInputs) nimDeps);
+
+  copyNimDeps = ''
+    mkdir -p $NIMBLE_DIR/pkgs
+    if [ ! -f $NIMBLE_DIR/packages_official.json ]; then
+      echo "[]" > $NIMBLE_DIR/packages_official.json
+    fi
+    '' + toString (map (dep: ''
+      if [ -d ${dep}/.nimble ]; then
+        cp -R ${dep}/.nimble/pkgs $NIMBLE_DIR
+      else
+        cp -R ${dep} $NIMBLE_DIR/pkgs/${dep.name}
+      fi
+    ''
+    ) nimDeps) + ''
+    # nimble >= 0.20.0 wants to store nimblemeta.json here
+    chmod -R u+w $NIMBLE_DIR/pkgs
+  '';
 in
 stdenv.mkDerivation {
   name = name;
@@ -24,34 +43,29 @@ stdenv.mkDerivation {
   nimDeps = nimDeps;
   patchPhase = patchPhase;
   LD_LIBRARY_PATH = makeLibraryPath (rBuildInputs ++ rNativeBuildInputs);
+
   buildPhase = ''
     HOME=$TMPDIR
-    mkdir -p $HOME/.nimble/pkgs
-    echo "[]" > $HOME/.nimble/packages_official.json
-    '' + toString (map (dep: ''
-      if [ -d ${dep}/.nimble ]; then
-        cp -R ${dep}/.nimble/pkgs $HOME/.nimble/
-      else
-        cp -R ${dep} $HOME/.nimble/pkgs/${dep.name}
-      fi
-      # nimble >= 0.20.0 wants to store a nimblemeta.json here
-      chmod u+w $HOME/.nimble/pkgs/${dep.name}
-    ''
-    ) nimDeps) + ''
+    NIMBLE_DIR=$HOME/.nimble
+  '' + copyNimDeps + ''
     nimble install
   '';
+
   installPhase = ''
     mkdir $out
-    nimbleDir=$TMPDIR/.nimble
-    if [ -d $nimbleDir/bin ]; then
-      cp -RL $nimbleDir/bin $out
+    if [ -d $NIMBLE_DIR/bin ]; then
+      cp -RL $NIMBLE_DIR/bin $out
     fi
-    numberNimFiles=$(find $nimbleDir/pkgs/${name} -type f -name "*.nim" | wc -l)
-    numberDirectories=$(find $nimbleDir/pkgs/${name} -mindepth 1 -type d | wc -l)
+    numberNimFiles=$(find $NIMBLE_DIR/pkgs/${name} -type f -name "*.nim" | wc -l)
+    numberDirectories=$(find $NIMBLE_DIR/pkgs/${name} -mindepth 1 -type d | wc -l)
     if [ $numberNimFiles -gt 0 ] || [ $numberDirectories -gt 0 ]; then
       mkdir -p $out/.nimble
-      cp -R $nimbleDir/pkgs $out/.nimble
+      cp -R $NIMBLE_DIR/pkgs $out/.nimble
     fi
   '';
+
+  shellHook = ''
+    export NIMBLE_DIR=$PWD/.nimble
+  '' + copyNimDeps;
 }