diff --git a/sys/powerpc/powerpc/vm_machdep.c b/sys/powerpc/powerpc/vm_machdep.c
index 4aab71ec036c..cfa9fe3c43b2 100644
--- a/sys/powerpc/powerpc/vm_machdep.c
+++ b/sys/powerpc/powerpc/vm_machdep.c
@@ -86,6 +86,7 @@
 #include <sys/sysent.h>
 #include <sys/unistd.h>
 
+#include <machine/altivec.h>
 #include <machine/cpu.h>
 #include <machine/fpu.h>
 #include <machine/frame.h>
@@ -121,6 +122,10 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
 	if ((flags & RFPROC) == 0)
 		return;
 
+	/* Ensure FP/VSX/Altivec state is up to date. */
+	save_fpu_nodrop(td1);
+	save_vec_nodrop(td1);
+
 	pcb = (struct pcb *)((td2->td_kstack +
 	    td2->td_kstack_pages * PAGE_SIZE - sizeof(struct pcb)) & ~0x2fUL);
 	td2->td_pcb = pcb;