diff --git a/SheepShaver/src/kpx_cpu/include/nvmemfun.hpp b/SheepShaver/src/kpx_cpu/include/nvmemfun.hpp
index 4d64b7bc..b8d15afe 100644
--- a/SheepShaver/src/kpx_cpu/include/nvmemfun.hpp
+++ b/SheepShaver/src/kpx_cpu/include/nvmemfun.hpp
@@ -27,6 +27,8 @@
 
 template< class PMF, class PF >
 inline PF nv_mem_fun_of(PMF pmf) {
+	if (pmf == NULL)
+		return NULL;
 	union { PMF pmf; uintptr p[2]; } x;
 	x.pmf = pmf;
 #if defined(__GXX_ABI_VERSION) /* GCC >= 3.0 */