diff --git a/CMakeLists.txt b/CMakeLists.txt
index 280fb776..3532c46f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -165,6 +165,9 @@ endif()
 
 find_package(Qt4 4.6.0 REQUIRED ${QT_REQUIRED_MODULES})
 include(${QT_USE_FILE})
+# Debian sets the the build type to None for package builds.
+# Make sure we don't enable asserts there.
+set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS_NONE QT_NO_DEBUG)
 
 find_package(Gcrypt REQUIRED)
 if(NOT (${GCRYPT_VERSION_STRING} VERSION_LESS "1.6.0"))