diff --git a/include/sbi/sbi_hsm.h b/include/sbi/sbi_hsm.h
index 11ae3ac3..65aff9f1 100644
--- a/include/sbi/sbi_hsm.h
+++ b/include/sbi/sbi_hsm.h
@@ -17,6 +17,7 @@
 #define SBI_HART_STOPPING	1
 #define SBI_HART_STARTING	2
 #define SBI_HART_STARTED	3
+#define SBI_HART_UNKNOWN	4
 
 int sbi_hsm_init(struct sbi_scratch *scratch, u32 hartid, bool cold_boot);
 void __noreturn sbi_hsm_exit(struct sbi_scratch *scratch);
diff --git a/lib/sbi/sbi_hsm.c b/lib/sbi/sbi_hsm.c
index b4034237..12199241 100644
--- a/lib/sbi/sbi_hsm.c
+++ b/lib/sbi/sbi_hsm.c
@@ -61,6 +61,9 @@ int sbi_hsm_hart_get_state(u32 hartid)
 	struct sbi_scratch *scratch;
 
 	scratch = sbi_hartid_to_scratch(hartid);
+	if (!scratch)
+		return SBI_HART_UNKNOWN;
+
 	hdata = sbi_scratch_offset_ptr(scratch, hart_data_offset);
 
 	return atomic_read(&hdata->state);
@@ -165,6 +168,9 @@ int sbi_hsm_init(struct sbi_scratch *scratch, u32 hartid, bool cold_boot)
 		/* Initialize hart state data for every hart */
 		for (i = 0; i < hart_count; i++) {
 			rscratch = sbi_hartid_to_scratch(i);
+			if (!rscratch)
+				continue;
+
 			hdata = sbi_scratch_offset_ptr(rscratch,
 						       hart_data_offset);
 			ATOMIC_INIT(&hdata->state,
@@ -212,14 +218,17 @@ fail_exit:
 int sbi_hsm_hart_start(struct sbi_scratch *scratch, u32 hartid,
 		       ulong saddr, ulong priv)
 {
+	int rc;
 	unsigned long init_count;
 	unsigned int hstate;
-	int rc;
+	struct sbi_scratch *rscratch;
+	struct sbi_hsm_data *hdata;
 	const struct sbi_platform *plat = sbi_platform_ptr(scratch);
-	struct sbi_scratch *rscratch = sbi_hartid_to_scratch(hartid);
-	struct sbi_hsm_data *hdata = sbi_scratch_offset_ptr(rscratch,
-							    hart_data_offset);
 
+	rscratch = sbi_hartid_to_scratch(hartid);
+	if (!rscratch)
+		return SBI_EINVAL;
+	hdata = sbi_scratch_offset_ptr(rscratch, hart_data_offset);
 	if (sbi_platform_hart_disabled(plat, hartid))
 		return SBI_EINVAL;
 	hstate = arch_atomic_cmpxchg(&hdata->state, SBI_HART_STOPPED,
diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c
index 69015281..f75b904a 100644
--- a/lib/sbi/sbi_init.c
+++ b/lib/sbi/sbi_init.c
@@ -305,6 +305,9 @@ unsigned long sbi_init_count(u32 hartid)
 		return 0;
 
 	scratch = sbi_hartid_to_scratch(hartid);
+	if (!scratch)
+		return 0;
+
 	init_count = sbi_scratch_offset_ptr(scratch, init_count_offset);
 
 	return *init_count;
diff --git a/lib/sbi/sbi_ipi.c b/lib/sbi/sbi_ipi.c
index fdd6e8ae..78db7520 100644
--- a/lib/sbi/sbi_ipi.c
+++ b/lib/sbi/sbi_ipi.c
@@ -41,11 +41,10 @@ static int sbi_ipi_send(struct sbi_scratch *scratch, u32 remote_hartid,
 		return SBI_EINVAL;
 	ipi_ops = ipi_ops_array[event];
 
-	/*
-	 * Set IPI type on remote hart's scratch area and
-	 * trigger the interrupt
-	 */
 	remote_scratch = sbi_hartid_to_scratch(remote_hartid);
+	if (!remote_scratch)
+		return SBI_EINVAL;
+
 	ipi_data = sbi_scratch_offset_ptr(remote_scratch, ipi_data_off);
 
 	if (ipi_ops->update) {
@@ -55,6 +54,10 @@ static int sbi_ipi_send(struct sbi_scratch *scratch, u32 remote_hartid,
 			return ret;
 	}
 
+	/*
+	 * Set IPI type on remote hart's scratch area and
+	 * trigger the interrupt
+	 */
 	atomic_raw_set_bit(event, &ipi_data->ipi_type);
 	smp_wmb();
 	sbi_platform_ipi_send(plat, remote_hartid);
diff --git a/lib/sbi/sbi_scratch.c b/lib/sbi/sbi_scratch.c
index 4dac8f7b..2d03a60a 100644
--- a/lib/sbi/sbi_scratch.c
+++ b/lib/sbi/sbi_scratch.c
@@ -72,6 +72,8 @@ done:
 		plat = sbi_platform_ptr(scratch);
 		for (i = 0; i < sbi_platform_hart_count(plat); i++) {
 			rscratch = sbi_hartid_to_scratch(i);
+			if (!rscratch)
+				continue;
 			ptr = sbi_scratch_offset_ptr(rscratch, ret);
 			sbi_memset(ptr, 0, size);
 		}
diff --git a/lib/sbi/sbi_tlb.c b/lib/sbi/sbi_tlb.c
index aab0d877..1b66fdf2 100644
--- a/lib/sbi/sbi_tlb.c
+++ b/lib/sbi/sbi_tlb.c
@@ -197,6 +197,9 @@ static void sbi_tlb_entry_process(struct sbi_tlb_info *tinfo)
 
 	sbi_hartmask_for_each_hart(rhartid, &tinfo->smask) {
 		rscratch = sbi_hartid_to_scratch(rhartid);
+		if (!rscratch)
+			continue;
+
 		rtlb_sync = sbi_scratch_offset_ptr(rscratch, tlb_sync_off);
 		while (atomic_raw_xchg_ulong(rtlb_sync, 1)) ;
 	}