diff --git a/vmtool.sh b/vmtool.sh
index f26432f..df1ba55 100755
--- a/vmtool.sh
+++ b/vmtool.sh
@@ -32,9 +32,24 @@ if ! command -v qemu-system-"$EMU_ARCH" > /dev/null 2>&1; then
     exit 1
 fi
 
-start() {
+stop() {
     for ((i=0;i<NUM_NODES;i++))
     do
+        pkill -F "$STATE_DIR"/node$i.pid >/dev/null 2>&1
+        rm -f "$STATE_DIR"/node$i.pid
+    done
+}
+
+start() {
+    stop
+
+    for ((i=0;i<NUM_NODES;i++))
+    do
+        if ! [ -f "$STATE_DIR"/node$i.qcow2 ] || ! [ -f "$STATE_DIR"/node$i-cloudinit.iso ]; then
+            echo "Missing disk images. Run create first."
+            exit 1
+        fi
+
         echo "Starting node $i"
         qemu-system-x86_64 \
             -enable-kvm \
@@ -75,14 +90,6 @@ start() {
     echo "Where # is the node number you want to reach."
 }
 
-stop() {
-    for ((i=0;i<NUM_NODES;i++))
-    do
-        pkill -F "$STATE_DIR"/node$i.pid >/dev/null 2>&1
-        rm -f "$STATE_DIR"/node$i.pid
-    done
-}
-
 destroy() {
     stop
 
@@ -160,6 +167,10 @@ create() {
 }
 
 case $1 in
+    start)
+        shift
+        start "$@"
+        ;;
     stop)
         shift
         stop "$@"