diff --git a/apps/Arm/vm_cross_connector/CMakeLists.txt b/apps/Arm/vm_cross_connector/CMakeLists.txt
index 24864ed3..071fee89 100644
--- a/apps/Arm/vm_cross_connector/CMakeLists.txt
+++ b/apps/Arm/vm_cross_connector/CMakeLists.txt
@@ -35,6 +35,8 @@ elseif(KernelPlatformQEMUArmVirt)
     if(SIMULATION)
         GenerateSimulateScript()
     endif()
+else()
+    message(FATAL_ERROR "unsupported platform")
 endif()
 
 AddToFileServer("linux" "${CAMKES_VM_IMAGES_DIR}/${KernelARMPlatform}/linux")
diff --git a/apps/Arm/vm_introspect/CMakeLists.txt b/apps/Arm/vm_introspect/CMakeLists.txt
index 5563d6db..51fce813 100644
--- a/apps/Arm/vm_introspect/CMakeLists.txt
+++ b/apps/Arm/vm_introspect/CMakeLists.txt
@@ -52,6 +52,8 @@ elseif(KernelPlatformQEMUArmVirt)
         GenerateSimulateScript()
     endif()
 
+else()
+    message(FATAL_ERROR "unsupported platform")
 endif()
 
 AddToFileServer("linux" "${CAMKES_VM_IMAGES_DIR}/${KernelARMPlatform}/linux")
diff --git a/apps/Arm/vm_minimal/CMakeLists.txt b/apps/Arm/vm_minimal/CMakeLists.txt
index 43255b2d..2c38ffcc 100644
--- a/apps/Arm/vm_minimal/CMakeLists.txt
+++ b/apps/Arm/vm_minimal/CMakeLists.txt
@@ -128,6 +128,9 @@ elseif(KernelPlatformOdroidc2)
         output_dtb_location
     )
     AddToFileServer("linux-dtb" "${output_dtb_location}" DEPENDS dtb_gen_target)
+
+else()
+    message(FATAL_ERROR "unsupported platform")
 endif()
 
 AddCamkesCPPFlag(cpp_flags CONFIG_VARS VmEmmc2NoDMA VmVUSB Tk1DeviceFwd Tk1Insecure)
diff --git a/apps/Arm/vm_multi/CMakeLists.txt b/apps/Arm/vm_multi/CMakeLists.txt
index cfa4f15d..639580ea 100644
--- a/apps/Arm/vm_multi/CMakeLists.txt
+++ b/apps/Arm/vm_multi/CMakeLists.txt
@@ -22,6 +22,8 @@ elseif(KernelPlatformQEMUArmVirt)
     if(SIMULATION)
         GenerateSimulateScript()
     endif()
+else()
+    message(FATAL_ERROR "unsupported platform")
 endif()
 
 # Generate our overlayed rootfs images
diff --git a/apps/Arm/vm_virtio_net/CMakeLists.txt b/apps/Arm/vm_virtio_net/CMakeLists.txt
index 66dbf272..30f31a6d 100644
--- a/apps/Arm/vm_virtio_net/CMakeLists.txt
+++ b/apps/Arm/vm_virtio_net/CMakeLists.txt
@@ -26,6 +26,9 @@ elseif(KernelPlatformTx2)
     set(rootfs_address "0xf7000000")
     set(dtb_file "${CAMKES_VM_IMAGES_DIR}/${KernelARMPlatform}/linux-pci-dtb")
     set(rootfs_file "${CAMKES_VM_IMAGES_DIR}/${KernelARMPlatform}/rootfs_crossvm.cpio.gz")
+
+else()
+    message(FATAL_ERROR "unsupported platform")
 endif()
 
 # Generate overlayed rootfs