diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
index 78c5afe98359..f8e9eb49d46b 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -498,7 +498,7 @@ static int __init probe_memory_block_size(unsigned long node, const char *uname,
 					  depth, void *data)
 {
 	unsigned long *mem_block_size = (unsigned long *)data;
-	const __be64 *prop;
+	const __be32 *prop;
 	int len;
 
 	if (depth != 1)
@@ -508,13 +508,14 @@ static int __init probe_memory_block_size(unsigned long node, const char *uname,
 		return 0;
 
 	prop = of_get_flat_dt_prop(node, "ibm,lmb-size", &len);
-	if (!prop || len < sizeof(__be64))
+
+	if (!prop || len < dt_root_size_cells * sizeof(__be32))
 		/*
 		 * Nothing in the device tree
 		 */
 		*mem_block_size = MIN_MEMORY_BLOCK_SIZE;
 	else
-		*mem_block_size = be64_to_cpup(prop);
+		*mem_block_size = of_read_number(prop, dt_root_size_cells);
 	return 1;
 }
 
diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index ca5589a1ec7f..4e18653a3804 100644
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -30,12 +30,17 @@ unsigned long pseries_memory_block_size(void)
 
 	np = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
 	if (np) {
-		const __be64 *size;
+		int len;
+		int size_cells;
+		const __be32 *prop;
 
-		size = of_get_property(np, "ibm,lmb-size", NULL);
-		if (size)
-			memblock_size = be64_to_cpup(size);
+		size_cells = of_n_size_cells(np);
+
+		prop = of_get_property(np, "ibm,lmb-size", &len);
+		if (prop && len >= size_cells * sizeof(__be32))
+			memblock_size = of_read_number(prop, size_cells);
 		of_node_put(np);
+
 	} else  if (machine_is(pseries)) {
 		/* This fallback really only applies to pseries */
 		unsigned int memzero_size = 0;