SoClassRegistry.m:129:52: warning: incompatible pointer types sending 'Class' to parameter of type 'id<NSCopying>' [-Wincompatible-pointer-types]
  129 |   if ((soClass = [self->objcToSoClass objectForKey:_clazz]))
      |                                                    ^~~~~~
SoClassRegistry.m:139:49: warning: incompatible pointer types sending 'Class' to parameter of type 'id<NSCopying>' [-Wincompatible-pointer-types]
  139 |   [self->objcToSoClass setObject:soClass forKey:_clazz];
      |      
Index: sope-appserver/NGObjWeb/SoObjects/GNUmakefile.preamble
--- sope-appserver/NGObjWeb/SoObjects/GNUmakefile.preamble.orig
+++ sope-appserver/NGObjWeb/SoObjects/GNUmakefile.preamble
@@ -4,7 +4,7 @@ include ../../../config.make
 
 ADDITIONAL_INCLUDE_DIRS += -I../WebDAV/
 
-ADDITIONAL_CPPFLAGS += -DCOMPILING_NGOBJWEB=1 -DCOMPILE_FOR_GNUSTEP=1
+ADDITIONAL_CPPFLAGS += -DCOMPILING_NGOBJWEB=1 -DCOMPILE_FOR_GNUSTEP=1 -Wno-error=incompatible-pointer-types
 
 # Parameters for SoProduct lookup
 
