diff --git a/CMakeLists.txt b/CMakeLists.txt
index 466d659..8bc18e1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -64,6 +64,9 @@ if(NOT foonathan_memory_FOUND)
         list(APPEND extra_cmake_args "-DANDROID_TOOLCHAIN_NAME=${ANDROID_TOOLCHAIN_NAME}")
       endif()
     endif()
+    if(QNX)
+      list(APPEND extra_cmake_args "-DCMAKE_SYSTEM_PROCESSOR=${CPUVARDIR}")
+    endif()
   endif()
   include(ExternalProject)