diff --git a/CMakeLists.txt b/CMakeLists.txt
index ae03bef4..18bcbeb8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -158,9 +158,18 @@ option(EVENT__COVERAGE
 
 # Put the libaries and binaries that get built into directories at the
 # top of the build tree rather than in hard-to-find leaf directories.
-set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/bin)
-set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/lib)
-set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/lib)
+#
+# But only if this variables are not defined yet
+# (i.e. libevent is used via add_subdirectory())
+if (NOT DEFINED CMAKE_RUNTIME_OUTPUT_DIRECTORY)
+    set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/bin)
+endif()
+if (NOT DEFINED CMAKE_LIBRARY_OUTPUT_DIRECTORY)
+    set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/lib)
+endif()
+if (NOT DEFINED CMAKE_ARCHIVE_OUTPUT_DIRECTORY)
+    set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/lib)
+endif()
 
 if (EVENT__ENABLE_VERBOSE_DEBUG)
     add_definitions(-DUSE_DEBUG=1)