diff --git a/validator/src/main/java/io/smallrye/config/validator/BeanValidationConfigValidator.java b/validator/src/main/java/io/smallrye/config/validator/BeanValidationConfigValidator.java
index b21f7f443..8f8f31a42 100644
--- a/validator/src/main/java/io/smallrye/config/validator/BeanValidationConfigValidator.java
+++ b/validator/src/main/java/io/smallrye/config/validator/BeanValidationConfigValidator.java
@@ -152,6 +152,35 @@ default void validateProperty(
                         throw new UndeclaredThrowableException(t2);
                     }
                 }
+            } else if (mapProperty.getValueProperty().isCollection()) {
+                try {
+                    CollectionProperty collectionProperty = mapProperty.getValueProperty().asCollection();
+                    if (collectionProperty.getElement().isGroup()) {
+                        Map<?, ?> map = (Map<?, ?>) property.getMethod().invoke(mappingObject);
+                        for (Map.Entry<?, ?> entry : map.entrySet()) {
+                            Collection<?> elements = (Collection<?>) entry.getValue();
+                            int i = 0;
+                            for (Object element : elements) {
+                                validateMappingInterface(collectionProperty.getElement().asGroup().getGroupType(),
+                                        appendPropertyName(currentPath, property) + "." + entry.getKey() + "[" + i + "]",
+                                        namingStrategy, element, problems);
+                                i++;
+                            }
+                        }
+                    } else if (collectionProperty.getElement().isLeaf()) {
+                        validatePropertyValue(property, currentPath, namingStrategy, mappingObject, problems);
+                    }
+                } catch (IllegalAccessException e) {
+                    throw new IllegalAccessError(e.getMessage());
+                } catch (InvocationTargetException e) {
+                    try {
+                        throw e.getCause();
+                    } catch (RuntimeException | Error e2) {
+                        throw e2;
+                    } catch (Throwable t2) {
+                        throw new UndeclaredThrowableException(t2);
+                    }
+                }
             } else if (mapProperty.getValueProperty().isLeaf()) {
                 validatePropertyValue(property, currentPath, namingStrategy, mappingObject, problems);
             }
@@ -224,6 +253,6 @@ default String interpolateMessage(
                 }
             }
         }
-        return propertyName.toString() + " " + violation.getMessage();
+        return propertyName + " " + violation.getMessage();
     }
 }
diff --git a/validator/src/test/java/io/smallrye/config/validator/ValidateConfigTest.java b/validator/src/test/java/io/smallrye/config/validator/ValidateConfigTest.java
index 4a6aaf165..6f9eccfb1 100644
--- a/validator/src/test/java/io/smallrye/config/validator/ValidateConfigTest.java
+++ b/validator/src/test/java/io/smallrye/config/validator/ValidateConfigTest.java
@@ -47,7 +47,10 @@ void validateConfigMapping() {
                         "server.info.name", "Bond",
                         "server.info.code", "007",
                         "server.info.alias[0]", "James",
-                        "server.info.admins.root.username", "root"))
+                        "server.info.admins.root[0].username", "root",
+                        "server.info.admins.root[1].username", "admin",
+                        "server.info.firewall.accepted[0]", "127.0.0.1",
+                        "server.info.firewall.accepted[1]", "8.8.8"))
                 .withMapping(Server.class, "server")
                 .build();
 
@@ -57,6 +60,7 @@ void validateConfigMapping() {
         for (int i = 0; i < validationException.getProblemCount(); i++) {
             validations.add(validationException.getProblem(i).getMessage());
         }
+        assertEquals(14, validations.size());
         assertTrue(validations.contains("server.port must be less than or equal to 10"));
         assertTrue(validations.contains("server.log.days must be less than or equal to 15"));
         assertTrue(validations.contains("server.proxy.timeout must be less than or equal to 10"));
@@ -69,7 +73,8 @@ void validateConfigMapping() {
         assertTrue(validations.contains("server.info.name size must be between 0 and 3"));
         assertTrue(validations.contains("server.info.code must be less than or equal to 3"));
         assertTrue(validations.contains("server.info.alias[0] size must be between 0 and 3"));
-        assertTrue(validations.contains("server.info.admins.root.username size must be between 0 and 3"));
+        assertTrue(validations.contains("server.info.admins.root[1].username size must be between 0 and 4"));
+        assertTrue(validations.contains("server.info.firewall.accepted[1] size must be between 8 and 15"));
     }
 
     @Test
@@ -173,10 +178,12 @@ interface Info {
 
             Optional<List<@Size(max = 3) String>> alias();
 
-            Map<String, Admin> admins();
+            Map<String, List<Admin>> admins();
+
+            Map<String, List<@Size(min = 8, max = 15) String>> firewall();
 
             interface Admin {
-                @Size(max = 3)
+                @Size(max = 4)
                 String username();
             }
         }