diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2c9e50131125b7d0e352a56afe5d89967cc51d08..d0ec916c5e0a4a90b9b082c72b24fcc5b3343c59 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -30,6 +30,15 @@ else()
 endif()
 if (Simox_FOUND)
 	setupSimoxExternalLibraries()
+    if(ARMARX_USE_QT5)
+        if(Simox_USE_QT4)
+            message(FATAL_ERROR "ArmarX uses Qt5 and Simox uses Qt4")
+        endif()
+    else()
+        if(Simox_USE_QT5)
+            message(FATAL_ERROR "ArmarX uses Qt4 and Simox uses Qt5")
+        endif()
+    endif()
 endif()
 
 add_subdirectory(source)