diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 0e50fa81..d1f4f5a2 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,12 +1,13 @@
 
 cmake_minimum_required(VERSION 3.1)
 
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
+include(DisallowInSource)
+
 project(Iaito VERSION 1.0.0)
 
 set(CMAKE_CXX_STANDARD 11)
 
-list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
-
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 set(CMAKE_AUTOMOC ON)
 set(CMAKE_AUTOUIC ON)
@@ -42,7 +43,10 @@ endif()
 
 # Parse iaito.pro to get filenames
 include(QMakeProParse)
-parse_qmake_pro("${CMAKE_CURRENT_SOURCE_DIR}/iaito.pro" IAITO_PRO)
+configure_file("${CMAKE_CURRENT_SOURCE_DIR}/iaito.pro"
+        "${CMAKE_CURRENT_BINARY_DIR}/iaito.pro"
+        COPYONLY) # trigger reconfigure if iaito.pro changes
+parse_qmake_pro("${CMAKE_CURRENT_BINARY_DIR}/iaito.pro" IAITO_PRO)
 set(SOURCE_FILES ${IAITO_PRO_SOURCES})
 set(HEADER_FILES ${IAITO_PRO_HEADERS})
 set(UI_FILES ${IAITO_PRO_FORMS})
diff --git a/src/cmake/DisallowInSource.cmake b/src/cmake/DisallowInSource.cmake
new file mode 100644
index 00000000..43e5c9e6
--- /dev/null
+++ b/src/cmake/DisallowInSource.cmake
@@ -0,0 +1,13 @@
+function(DisallowInSource)
+	get_filename_component(SRC_DIR_REALPATH "${CMAKE_SOURCE_DIR}" REALPATH)
+	get_filename_component(BINARY_DIR_REALPATH "${CMAKE_BINARY_DIR}" REALPATH)
+	if(SRC_DIR_REALPATH STREQUAL BINARY_DIR_REALPATH)
+		message(FATAL_ERROR " In-source builds are not allowed.
+ Please create a directory and run cmake from there:
+ mkdir build && cd build && cmake ..
+ This process created the file CMakeCache.txt and the directory CMakeFiles in ${CMAKE_SOURCE_DIR}.
+ Please delete them manually!")
+	endif()
+endfunction()
+
+DisallowInSource()
\ No newline at end of file