diff --git a/services/std_svc/psci/psci_afflvl_off.c b/services/std_svc/psci/psci_afflvl_off.c
index e007bc3..21a4d1a 100644
--- a/services/std_svc/psci/psci_afflvl_off.c
+++ b/services/std_svc/psci/psci_afflvl_off.c
@@ -82,6 +82,7 @@
 	sctlr = read_sctlr_el3();
 	sctlr &= ~SCTLR_C_BIT;
 	write_sctlr_el3(sctlr);
+	isb();	/* ensure MMU disable takes immediate effect */
 
 	/*
 	 * CAUTION: This flush to the level of unification makes an assumption
diff --git a/services/std_svc/psci/psci_afflvl_suspend.c b/services/std_svc/psci/psci_afflvl_suspend.c
index dc12f7a..534e4a9 100644
--- a/services/std_svc/psci/psci_afflvl_suspend.c
+++ b/services/std_svc/psci/psci_afflvl_suspend.c
@@ -198,6 +198,7 @@
 	sctlr = read_sctlr_el3();
 	sctlr &= ~SCTLR_C_BIT;
 	write_sctlr_el3(sctlr);
+	isb();	/* ensure MMU disable takes immediate effect */
 
 	/*
 	 * CAUTION: This flush to the level of unification makes an assumption
diff --git a/services/std_svc/psci/psci_entry.S b/services/std_svc/psci/psci_entry.S
index e2c690d..ec55a81 100644
--- a/services/std_svc/psci/psci_entry.S
+++ b/services/std_svc/psci/psci_entry.S
@@ -75,7 +75,6 @@
 	 * ---------------------------------------------
 	 */
 	msr	spsel, #0
-	isb
 
 	bl	read_mpidr
 	mov	x19, x0
@@ -158,7 +157,7 @@
 	ret
 
 func final_wfi
-	dsb	sy
+	dsb	sy		// ensure write buffer empty
 	wfi
 wfi_spill:
 	b	wfi_spill