diff --git a/nix/shell.sh b/nix/shell.sh
index 348ffe8848..497ea385fb 100755
--- a/nix/shell.sh
+++ b/nix/shell.sh
@@ -1,19 +1,29 @@
 #!/usr/bin/env bash
 
+#
+# This script is used by the Makefile to have an implicit nix-shell.
+#
+
 GREEN='\033[0;32m'
 NC='\033[0m'
 
 export TERM=xterm # fix for colors
 shift # we remove the first -c from arguments
+
 if ! command -v "nix" >/dev/null 2>&1; then
-  echo -e "${GREEN}Setting up environment...${NC}"
-  ./scripts/setup
-fi
-if command -v "nix" >/dev/null 2>&1 || [ -f ~/.nix-profile/etc/profile.d/nix.sh ]; then
-  echo -e "${GREEN}Configuring Nix shell...${NC}";
-  if [[ $@ == "ENTER_NIX_SHELL" ]]; then
-    . ~/.nix-profile/etc/profile.d/nix.sh && exec nix-shell
+  if [ -f ~/.nix-profile/etc/profile.d/nix.sh ]; then
+    . ~/.nix-profile/etc/profile.d/nix.sh
   else
-    . ~/.nix-profile/etc/profile.d/nix.sh && exec nix-shell --run "$@"
+    echo -e "${GREEN}Setting up environment...${NC}"
+    ./scripts/setup
+  fi
+fi
+
+if command -v "nix" >/dev/null 2>&1; then
+  echo -e "${GREEN}Configuring Nix shell...${NC}";
+  if [[ $@ == "ENTER_NIX_SHELL" ]]; then
+    exec nix-shell
+  else
+    exec nix-shell --run "$@"
   fi
 fi