diff --git a/src/document/dom/node.c b/src/document/dom/node.c
index 3ab91d55..043f553f 100644
--- a/src/document/dom/node.c
+++ b/src/document/dom/node.c
@@ -427,8 +427,8 @@ get_dom_node_value(struct dom_node *node, int codepage)
 			break;
 
 		case DOM_NODE_PROCESSING_INSTRUCTION:
-			value	 = node->data.proc_instruction.instruction;
-			valuelen = node->data.proc_instruction.instructionlen;
+			value	 = node->data.proc_instruction.instruction.string;
+			valuelen = node->data.proc_instruction.instruction.length;
 			break;
 
 		case DOM_NODE_CDATA_SECTION:
diff --git a/src/document/dom/node.h b/src/document/dom/node.h
index 3661f2ef..6313f9b6 100644
--- a/src/document/dom/node.h
+++ b/src/document/dom/node.h
@@ -160,8 +160,7 @@ struct dom_proc_instruction_node {
 	/* The target of the processing instruction (xml for '<?xml ...  ?>')
 	 * is in the @string / @length members. */
 	/* This holds the value to be processed */
-	unsigned char *instruction;
-	uint16_t instructionlen;
+	struct dom_string instruction;
 
 	/* For fast checking of the target type */
 	uint16_t type; /* enum dom_proc_instruction_type */
@@ -276,8 +275,7 @@ add_dom_proc_instruction(struct dom_node *parent, unsigned char *string, int len
 	struct dom_node *node = add_dom_node(parent, DOM_NODE_PROCESSING_INSTRUCTION, string, length);
 
 	if (node && instruction) {
-		node->data.proc_instruction.instruction    = instruction;
-		node->data.proc_instruction.instructionlen = instructionlen;
+		set_dom_string(&node->data.proc_instruction.instruction, instruction, instructionlen);
 	}
 
 	return node;
diff --git a/src/document/dom/renderer.c b/src/document/dom/renderer.c
index 05ccb0ae..7ea2a6e9 100644
--- a/src/document/dom/renderer.c
+++ b/src/document/dom/renderer.c
@@ -559,8 +559,8 @@ render_dom_proc_instr_source(struct dom_stack *stack, struct dom_node *node, voi
 
 	render_dom_node_text(renderer, &renderer->styles[node->type], node);
 
-	value	 = node->data.proc_instruction.instruction;
-	valuelen = node->data.proc_instruction.instructionlen;
+	value	 = node->data.proc_instruction.instruction.string;
+	valuelen = node->data.proc_instruction.instruction.length;
 
 	if (!value || node->data.proc_instruction.map)
 		return node;