diff --git a/CMakeLists.txt b/CMakeLists.txt
index 67bb1f319..bd4d3eb3a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -46,6 +46,9 @@ project( CALAMARES
 )
 
 set( CALAMARES_VERSION_RC 1 )  # Set to 0 during release cycle, 1 during development
+if( CALAMARES_VERSION_RC EQUAL 1 AND CMAKE_SOURCE_DIR STREQUAL CMAKE_BINARY_DIR )
+    message( FATAL_ERROR "Do not build development versions in the source-directory." )
+endif()
 
 ### OPTIONS
 #