diff --git a/src/backend/statistics/extended_stats.c b/src/backend/statistics/extended_stats.c
index cb7d6d04ce5..07b3610d24e 100644
--- a/src/backend/statistics/extended_stats.c
+++ b/src/backend/statistics/extended_stats.c
@@ -1432,6 +1432,8 @@ statext_is_compatible_clause_internal(PlannerInfo *root, Node *clause,
 
 			return true;
 		}
+		else
+			return false;
 	}
 
 	/* Var/Expr IN Array */
@@ -2137,13 +2139,13 @@ examine_opclause_args(List *args, Node **exprp, Const **cstp,
  * non-null pointers (exprp_left, exprp_right).
  */
 bool
-is_opclause_var_op_var(List *args, Node **exprp_left, Node **exprp_right)
+is_opclause_var_op_var(List *args, Node **expr_left, Node **expr_right)
 {
 	Node	   *leftop,
 			   *rightop;
-	Node	   *expr_left,
-			   *expr_right;
-	
+
+	*expr_left = NULL;
+	*expr_right = NULL;
 
 	/* enforced by statext_is_compatible_clause_internal */
 	Assert(list_length(args) == 2);
@@ -2157,20 +2159,16 @@ is_opclause_var_op_var(List *args, Node **exprp_left, Node **exprp_right)
 	if (IsA(rightop, RelabelType))
 		rightop = (Node *) ((RelabelType *) rightop)->arg;
 
+
 	if (IsA(rightop, Var) && IsA(leftop, Var))
 	{
-		expr_left = (Node *) leftop;
-		expr_right = (Node *) rightop;
+		*expr_left = (Node *) leftop;
+		*expr_right = (Node *) rightop;
 	}
 	else
 		return false;
 
-	/* return pointers to the extracted parts if requested */
-	if (exprp_left && exprp_right)
-	{
-		*exprp_left = expr_left;
-		*exprp_right = expr_right;
-	}
+	Assert(expr_left && expr_right);
 
 	return true;
 }
diff --git a/src/backend/statistics/mcv.c b/src/backend/statistics/mcv.c
index 2e2c028e0f0..dd1a1c0c829 100644
--- a/src/backend/statistics/mcv.c
+++ b/src/backend/statistics/mcv.c
@@ -1745,6 +1745,8 @@ mcv_get_match_bitmap(PlannerInfo *root, List *clauses,
 														   item->values[idx_right]));
 				}
 			}
+			else
+				elog(ERROR, "incompatible clause");
 		}
 		else if (IsA(clause, ScalarArrayOpExpr))
 		{