diff --git a/core/src/main/java/org/elasticsearch/index/query/RegexpQueryBuilder.java b/core/src/main/java/org/elasticsearch/index/query/RegexpQueryBuilder.java
index 7be77795e82..c0d8be286b4 100644
--- a/core/src/main/java/org/elasticsearch/index/query/RegexpQueryBuilder.java
+++ b/core/src/main/java/org/elasticsearch/index/query/RegexpQueryBuilder.java
@@ -229,6 +229,10 @@ public class RegexpQueryBuilder extends AbstractQueryBuilder<RegexpQueryBuilder>
                 if (parseContext.getParseFieldMatcher().match(currentFieldName, NAME_FIELD)) {
                     queryName = parser.text();
                 } else {
+                    if (fieldName != null) {
+                        throw new ParsingException(parser.getTokenLocation(), "[regexp] query doesn't support multiple fields, found ["
+                                + fieldName + "] and [" + parser.currentName() + "]");
+                    }
                     fieldName = currentFieldName;
                     value = parser.textOrNull();
                 }
diff --git a/core/src/test/java/org/elasticsearch/index/query/RegexpQueryBuilderTests.java b/core/src/test/java/org/elasticsearch/index/query/RegexpQueryBuilderTests.java
index 41cfc2c63ff..7daed416a05 100644
--- a/core/src/test/java/org/elasticsearch/index/query/RegexpQueryBuilderTests.java
+++ b/core/src/test/java/org/elasticsearch/index/query/RegexpQueryBuilderTests.java
@@ -135,5 +135,15 @@ public class RegexpQueryBuilderTests extends AbstractQueryTestCase<RegexpQueryBu
                 "}";
         ParsingException e = expectThrows(ParsingException.class, () -> parseQuery(json));
         assertEquals("[regexp] query doesn't support multiple fields, found [user1] and [user2]", e.getMessage());
+
+        String shortJson =
+                "{\n" +
+                "    \"regexp\": {\n" +
+                "      \"user1\": \"k.*y\",\n" +
+                "      \"user2\": \"k.*y\"\n" +
+                "    }\n" +
+                "}";
+        e = expectThrows(ParsingException.class, () -> parseQuery(shortJson));
+        assertEquals("[regexp] query doesn't support multiple fields, found [user1] and [user2]", e.getMessage());
     }
 }