diff --git a/README.md b/README.md
index c053a3d4..b2042c5c 100644
--- a/README.md
+++ b/README.md
@@ -262,6 +262,8 @@ In some cases it is necessary to install Debian 10 (Buster) on your own:
 
 The T-Pot Universal Installer will upgrade the system and install all required T-Pot dependencies.
 
+Important notice: The user / group `tpot` are reserved for T-Pot. The installation will abort if the user `tpot` exists. Make sure to use a different user name when preparing the OS installation for T-Pot.
+
 Just follow these steps:
 
 ```
diff --git a/iso/installer/install.sh b/iso/installer/install.sh
index a988ab22..57a478d7 100755
--- a/iso/installer/install.sh
+++ b/iso/installer/install.sh
@@ -436,6 +436,16 @@ if [ -s "$myTPOT_CONF_FILE" ] && [ "$myTPOT_CONF_FILE" != "" ];
 fi
 
 # Prepare running the installer
+myUSERCHECK=$(grep "tpot" /etc/passwd | wc -l)
+if [ "$myUSERCHECK" -gt "0" ];
+  then
+    echo "### The user name \"tpot\" already exists. The tpot username and group may not previously exist or T-Pot will not work."
+    echo "### We recommend a fresh install according to the T-Pot Readme Post-Install method."
+    echo
+    echo "Aborting."
+    echo
+    exit 0
+fi
 echo "$myINFO" | head -n 3
 fuCHECK_PORTS