diff --git a/cmake-modules/KDEPython.cmake b/cmake-modules/KDEPython.cmake
--- a/cmake-modules/KDEPython.cmake
+++ b/cmake-modules/KDEPython.cmake
@@ -48,19 +48,20 @@
     set(_message "Byte-compiling ${_bin_py} to ${_bin_pyc}")

     string(REPLACE "/" "_" _rule_name "${_basepath}/${_bin_pyc}")
-    add_custom_target("${_rule_name}" ALL)
+    string(REPLACE " " "_" __rule_name "${_rule_name}")
+    add_custom_target("${__rule_name}" ALL)

     get_filename_component(_abs_bin_py ${_bin_py} ABSOLUTE)
     if(_abs_bin_py STREQUAL _absfilename)    # Don't copy the file onto itself.
       add_custom_command(
-        TARGET "${_rule_name}"
+        TARGET "${__rule_name}"
         COMMAND "${CMAKE_COMMAND}" -E echo "${_message}"
         COMMAND "${PYTHON_EXECUTABLE}" "${_python_compile_py}" "--destination-dir" "${DESTINATION_DIR}" "${_bin_py}"
         DEPENDS "${_absfilename}"
       )
     else()
       add_custom_command(
-        TARGET "${_rule_name}"
+        TARGET "${__rule_name}"
         COMMAND "${CMAKE_COMMAND}" -E echo "${_message}"
         COMMAND "${CMAKE_COMMAND}" -E copy "${_absfilename}" "${_bin_py}"
         COMMAND "${PYTHON_EXECUTABLE}" "${_python_compile_py}" "--destination-dir" "${DESTINATION_DIR}" "${_bin_py}"