diff --git a/cmake/QtBuild.cmake b/cmake/QtBuild.cmake
index c372c42849..66ef694121 100644
--- a/cmake/QtBuild.cmake
+++ b/cmake/QtBuild.cmake
@@ -319,6 +319,16 @@ elseif(QNX)
             set(QT_DEFAULT_MKSPEC qnx-${arch}-qcc)
         endif()
     endforeach()
+elseif(FREEBSD)
+    if(CLANG)
+        set(QT_DEFAULT_MKSPEC freebsd-clang)
+    elseif(GCC)
+        set(QT_DEFAULT_MKSPEC freebsd-g++)
+    endif()
+elseif(NETBSD)
+    set(QT_DEFAULT_MKSPEC netbsd-g++)
+elseif(OPENBSD)
+    set(QT_DEFAULT_MKSPEC openbsd-g++)
 endif()
 
 if(NOT QT_QMAKE_TARGET_MKSPEC)