diff --git a/arch/powerpc/sysdev/fsl_mpic_err.c b/arch/powerpc/sysdev/fsl_mpic_err.c
index 488ec453038a..2a98837dc6ba 100644
--- a/arch/powerpc/sysdev/fsl_mpic_err.c
+++ b/arch/powerpc/sysdev/fsl_mpic_err.c
@@ -76,7 +76,7 @@ int mpic_setup_error_int(struct mpic *mpic, int intvec)
 	mpic->flags |= MPIC_FSL_HAS_EIMR;
 	/* allocate interrupt vectors for error interrupts */
 	for (i = MPIC_MAX_ERR - 1; i >= 0; i--)
-		mpic->err_int_vecs[i] = --intvec;
+		mpic->err_int_vecs[i] = intvec--;
 
 	return 0;
 }
diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index 353b43972bbf..934a77324f6b 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -1380,12 +1380,12 @@ struct mpic * __init mpic_alloc(struct device_node *node,
 		 * global vector number space, as in case of ipis
 		 * and timer interrupts.
 		 *
-		 * Available vector space = intvec_top - 12, where 12
+		 * Available vector space = intvec_top - 13, where 13
 		 * is the number of vectors which have been consumed by
-		 * ipis and timer interrupts.
+		 * ipis, timer interrupts and spurious.
 		 */
 		if (fsl_version >= 0x401) {
-			ret = mpic_setup_error_int(mpic, intvec_top - 12);
+			ret = mpic_setup_error_int(mpic, intvec_top - 13);
 			if (ret)
 				return NULL;
 		}