diff -rupN --no-dereference qt3d-everywhere-src-5.13.2/src/3rdparty/assimp/assimp.pri qt3d-everywhere-src-5.13.2-new/src/3rdparty/assimp/assimp.pri
--- qt3d-everywhere-src-5.13.2/src/3rdparty/assimp/assimp.pri	2019-10-21 07:57:22.000000000 +0200
+++ qt3d-everywhere-src-5.13.2-new/src/3rdparty/assimp/assimp.pri	2019-12-16 10:13:01.061066663 +0100
@@ -6,7 +6,9 @@ CONFIG -= precompile_header
 
 win32:DEFINES+=_CRT_SECURE_NO_WARNINGS
 
-qtConfig(system-zlib):!if(cross_compile:host_build): \
+cross_compile {
+    LIBS += -lz
+} else: qtConfig(system-zlib):!if(cross_compile:host_build): \
     QMAKE_USE_PRIVATE += zlib
 else: \
     QT_PRIVATE += zlib-private