diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index b8a0452565..06d498f029 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -133,13 +133,11 @@ _equalExtensibleNode(const ExtensibleNode *a, const ExtensibleNode *b)
 static bool
 _equalA_Const(const A_Const *a, const A_Const *b)
 {
-	/*
-	 * Hack for in-line val field.  Also val is not valid is isnull is true.
-	 */
-	if (!a->isnull && !b->isnull &&
+	COMPARE_SCALAR_FIELD(isnull);
+	/* Hack for in-line val field.  Also val is not valid if isnull is true */
+	if (!a->isnull &&
 		!equal(&a->val, &b->val))
 		return false;
-	COMPARE_SCALAR_FIELD(isnull);
 	COMPARE_LOCATION_FIELD(location);
 
 	return true;
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index f3629cdfd1..597e5b3ea8 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -305,6 +305,7 @@ _readA_Const(void)
 {
 	READ_LOCALS(A_Const);
 
+	/* We expect either NULL or :val here */
 	token = pg_strtok(&length);
 	if (length == 4 && strncmp(token, "NULL", 4) == 0)
 		local_node->isnull = true;
@@ -312,7 +313,29 @@ _readA_Const(void)
 	{
 		union ValUnion *tmp = nodeRead(NULL, 0);
 
-		memcpy(&local_node->val, tmp, sizeof(*tmp));
+		/* To forestall valgrind complaints, copy only the valid data */
+		switch (nodeTag(tmp))
+		{
+			case T_Integer:
+				memcpy(&local_node->val, tmp, sizeof(Integer));
+				break;
+			case T_Float:
+				memcpy(&local_node->val, tmp, sizeof(Float));
+				break;
+			case T_Boolean:
+				memcpy(&local_node->val, tmp, sizeof(Boolean));
+				break;
+			case T_String:
+				memcpy(&local_node->val, tmp, sizeof(String));
+				break;
+			case T_BitString:
+				memcpy(&local_node->val, tmp, sizeof(BitString));
+				break;
+			default:
+				elog(ERROR, "unrecognized node type: %d",
+					 (int) nodeTag(tmp));
+				break;
+		}
 	}
 
 	READ_LOCATION_FIELD(location);