diff --git a/sys/powerpc/pseries/mmu_phyp.c b/sys/powerpc/pseries/mmu_phyp.c
index a4131f504401..cdf5dfefea55 100644
--- a/sys/powerpc/pseries/mmu_phyp.c
+++ b/sys/powerpc/pseries/mmu_phyp.c
@@ -165,6 +165,11 @@ mphyp_bootstrap(mmu_t mmup, vm_offset_t kernelstart, vm_offset_t kernelend)
 				nptlp--;
 			}
 		}
+
+		/* For now we allow shift only to be <= 0x18. */
+		if (shift >= 0x18)
+		    shift = 0x18;
+
 		moea64_large_page_shift = shift;
 		moea64_large_page_size = 1ULL << shift;
 	}