diff --git a/sys/amd64/amd64/mp_machdep.c b/sys/amd64/amd64/mp_machdep.c
index 48d716a1f4ad..ca8cfd2714b0 100644
--- a/sys/amd64/amd64/mp_machdep.c
+++ b/sys/amd64/amd64/mp_machdep.c
@@ -1155,7 +1155,7 @@ static int
 processor_entry(proc_entry_ptr entry, int cpu)
 {
 	/* check for usability */
-	if ((cpu >= NCPU) || !(entry->cpu_flags & PROCENTRY_FLAG_EN))
+	if (!(entry->cpu_flags & PROCENTRY_FLAG_EN))
 		return 0;
 
 	/* check for BSP flag */
@@ -1167,11 +1167,13 @@ processor_entry(proc_entry_ptr entry, int cpu)
 	}
 
 	/* add another AP to list, if less than max number of CPUs */
-	else {
+	else if (cpu < NCPU) {
 		CPU_TO_ID(cpu) = entry->apic_id;
 		ID_TO_CPU(entry->apic_id) = cpu;
 		return 1;
 	}
+
+	return 0;
 }
 
 
diff --git a/sys/amd64/amd64/mptable.c b/sys/amd64/amd64/mptable.c
index 48d716a1f4ad..ca8cfd2714b0 100644
--- a/sys/amd64/amd64/mptable.c
+++ b/sys/amd64/amd64/mptable.c
@@ -1155,7 +1155,7 @@ static int
 processor_entry(proc_entry_ptr entry, int cpu)
 {
 	/* check for usability */
-	if ((cpu >= NCPU) || !(entry->cpu_flags & PROCENTRY_FLAG_EN))
+	if (!(entry->cpu_flags & PROCENTRY_FLAG_EN))
 		return 0;
 
 	/* check for BSP flag */
@@ -1167,11 +1167,13 @@ processor_entry(proc_entry_ptr entry, int cpu)
 	}
 
 	/* add another AP to list, if less than max number of CPUs */
-	else {
+	else if (cpu < NCPU) {
 		CPU_TO_ID(cpu) = entry->apic_id;
 		ID_TO_CPU(entry->apic_id) = cpu;
 		return 1;
 	}
+
+	return 0;
 }
 
 
diff --git a/sys/amd64/include/mptable.h b/sys/amd64/include/mptable.h
index 48d716a1f4ad..ca8cfd2714b0 100644
--- a/sys/amd64/include/mptable.h
+++ b/sys/amd64/include/mptable.h
@@ -1155,7 +1155,7 @@ static int
 processor_entry(proc_entry_ptr entry, int cpu)
 {
 	/* check for usability */
-	if ((cpu >= NCPU) || !(entry->cpu_flags & PROCENTRY_FLAG_EN))
+	if (!(entry->cpu_flags & PROCENTRY_FLAG_EN))
 		return 0;
 
 	/* check for BSP flag */
@@ -1167,11 +1167,13 @@ processor_entry(proc_entry_ptr entry, int cpu)
 	}
 
 	/* add another AP to list, if less than max number of CPUs */
-	else {
+	else if (cpu < NCPU) {
 		CPU_TO_ID(cpu) = entry->apic_id;
 		ID_TO_CPU(entry->apic_id) = cpu;
 		return 1;
 	}
+
+	return 0;
 }
 
 
diff --git a/sys/i386/i386/mp_machdep.c b/sys/i386/i386/mp_machdep.c
index 48d716a1f4ad..ca8cfd2714b0 100644
--- a/sys/i386/i386/mp_machdep.c
+++ b/sys/i386/i386/mp_machdep.c
@@ -1155,7 +1155,7 @@ static int
 processor_entry(proc_entry_ptr entry, int cpu)
 {
 	/* check for usability */
-	if ((cpu >= NCPU) || !(entry->cpu_flags & PROCENTRY_FLAG_EN))
+	if (!(entry->cpu_flags & PROCENTRY_FLAG_EN))
 		return 0;
 
 	/* check for BSP flag */
@@ -1167,11 +1167,13 @@ processor_entry(proc_entry_ptr entry, int cpu)
 	}
 
 	/* add another AP to list, if less than max number of CPUs */
-	else {
+	else if (cpu < NCPU) {
 		CPU_TO_ID(cpu) = entry->apic_id;
 		ID_TO_CPU(entry->apic_id) = cpu;
 		return 1;
 	}
+
+	return 0;
 }
 
 
diff --git a/sys/i386/i386/mptable.c b/sys/i386/i386/mptable.c
index 48d716a1f4ad..ca8cfd2714b0 100644
--- a/sys/i386/i386/mptable.c
+++ b/sys/i386/i386/mptable.c
@@ -1155,7 +1155,7 @@ static int
 processor_entry(proc_entry_ptr entry, int cpu)
 {
 	/* check for usability */
-	if ((cpu >= NCPU) || !(entry->cpu_flags & PROCENTRY_FLAG_EN))
+	if (!(entry->cpu_flags & PROCENTRY_FLAG_EN))
 		return 0;
 
 	/* check for BSP flag */
@@ -1167,11 +1167,13 @@ processor_entry(proc_entry_ptr entry, int cpu)
 	}
 
 	/* add another AP to list, if less than max number of CPUs */
-	else {
+	else if (cpu < NCPU) {
 		CPU_TO_ID(cpu) = entry->apic_id;
 		ID_TO_CPU(entry->apic_id) = cpu;
 		return 1;
 	}
+
+	return 0;
 }
 
 
diff --git a/sys/i386/include/mpapic.h b/sys/i386/include/mpapic.h
index a0099364a99f..4a387199381e 100644
--- a/sys/i386/include/mpapic.h
+++ b/sys/i386/include/mpapic.h
@@ -98,6 +98,8 @@ all_procs_ipi(int vector)
 static __inline int
 all_but_self_ipi(int vector)
 {
+	if (mp_ncpus <= 1)
+		return 0;
 	return apic_ipi(APIC_DEST_ALLESELF, vector, APIC_DELMODE_FIXED);
 }
 
diff --git a/sys/i386/include/mptable.h b/sys/i386/include/mptable.h
index 48d716a1f4ad..ca8cfd2714b0 100644
--- a/sys/i386/include/mptable.h
+++ b/sys/i386/include/mptable.h
@@ -1155,7 +1155,7 @@ static int
 processor_entry(proc_entry_ptr entry, int cpu)
 {
 	/* check for usability */
-	if ((cpu >= NCPU) || !(entry->cpu_flags & PROCENTRY_FLAG_EN))
+	if (!(entry->cpu_flags & PROCENTRY_FLAG_EN))
 		return 0;
 
 	/* check for BSP flag */
@@ -1167,11 +1167,13 @@ processor_entry(proc_entry_ptr entry, int cpu)
 	}
 
 	/* add another AP to list, if less than max number of CPUs */
-	else {
+	else if (cpu < NCPU) {
 		CPU_TO_ID(cpu) = entry->apic_id;
 		ID_TO_CPU(entry->apic_id) = cpu;
 		return 1;
 	}
+
+	return 0;
 }
 
 
diff --git a/sys/kern/subr_smp.c b/sys/kern/subr_smp.c
index 48d716a1f4ad..ca8cfd2714b0 100644
--- a/sys/kern/subr_smp.c
+++ b/sys/kern/subr_smp.c
@@ -1155,7 +1155,7 @@ static int
 processor_entry(proc_entry_ptr entry, int cpu)
 {
 	/* check for usability */
-	if ((cpu >= NCPU) || !(entry->cpu_flags & PROCENTRY_FLAG_EN))
+	if (!(entry->cpu_flags & PROCENTRY_FLAG_EN))
 		return 0;
 
 	/* check for BSP flag */
@@ -1167,11 +1167,13 @@ processor_entry(proc_entry_ptr entry, int cpu)
 	}
 
 	/* add another AP to list, if less than max number of CPUs */
-	else {
+	else if (cpu < NCPU) {
 		CPU_TO_ID(cpu) = entry->apic_id;
 		ID_TO_CPU(entry->apic_id) = cpu;
 		return 1;
 	}
+
+	return 0;
 }