diff --git a/extras/tests/JsonVariant/set.cpp b/extras/tests/JsonVariant/set.cpp
index bf4c951e..b10f9505 100644
--- a/extras/tests/JsonVariant/set.cpp
+++ b/extras/tests/JsonVariant/set.cpp
@@ -188,12 +188,12 @@ TEST_CASE("JsonVariant::set() when there is enough memory") {
   }
 
   SECTION("int64_t") {
-    bool result = variant.set(int64_t(-2147483649));
+    bool result = variant.set(int64_t(-2147483649LL));
     doc.shrinkToFit();
 
     REQUIRE(result == true);
     REQUIRE(variant.is<int64_t>() == true);
-    REQUIRE(variant.as<int64_t>() == -2147483649);
+    REQUIRE(variant.as<int64_t>() == -2147483649LL);
     REQUIRE(spy.log() ==
             AllocatorLog{
                 Allocate(sizeofPool()),
@@ -278,6 +278,34 @@ TEST_CASE("JsonVariant::set() with not enough memory") {
     REQUIRE(result == false);
     REQUIRE(v.isNull());
   }
+
+  SECTION("int32_t") {
+    bool result = v.set(-42);
+
+    REQUIRE(result == true);
+    REQUIRE(v.is<int32_t>());
+  }
+
+  SECTION("int64_t") {
+    bool result = v.set(-2147483649LL);
+
+    REQUIRE(result == false);
+    REQUIRE(v.isNull());
+  }
+
+  SECTION("uint32_t") {
+    bool result = v.set(42);
+
+    REQUIRE(result == true);
+    REQUIRE(v.is<uint32_t>());
+  }
+
+  SECTION("uint64_t") {
+    bool result = v.set(4294967296U);
+
+    REQUIRE(result == false);
+    REQUIRE(v.isNull());
+  }
 }
 
 TEST_CASE("JsonVariant::set() releases the previous value") {
@@ -325,29 +353,33 @@ TEST_CASE("JsonVariant::set() releases the previous value") {
   }
 }
 
-TEST_CASE("Extension slots") {
+TEST_CASE("JsonVariant::set() reuses extension slot") {
   SpyingAllocator spy;
   JsonDocument doc(&spy);
+  JsonVariant variant = doc.to<JsonVariant>();
 
-  SECTION("double requires two slot") {
-    int i = ARDUINOJSON_POOL_CAPACITY - 1;
+  variant.set(1.2);
+  doc.shrinkToFit();
+  spy.clearLog();
 
-    // make sure the pool is full
-    doc[i] = 1;
-    REQUIRE(spy.log() == AllocatorLog{
-                             Allocate(sizeofPool()),
-                         });
+  SECTION("double") {
+    bool result = variant.set(3.4);
 
-    // replace with a float => no allocation
-    spy.clearLog();
-    doc[i] = 1.2f;
+    REQUIRE(result == true);
     REQUIRE(spy.log() == AllocatorLog{});
+  }
 
-    // replace with a double => new pool needed
-    spy.clearLog();
-    doc[i] = 1.2;
-    REQUIRE(spy.log() == AllocatorLog{
-                             Allocate(sizeofPool()),
-                         });
+  SECTION("int64_t") {
+    bool result = variant.set(-2147483649LL);
+
+    REQUIRE(result == true);
+    REQUIRE(spy.log() == AllocatorLog{});
+  }
+
+  SECTION("uint64_t") {
+    bool result = variant.set(4294967296U);
+
+    REQUIRE(result == true);
+    REQUIRE(spy.log() == AllocatorLog{});
   }
 }
diff --git a/src/ArduinoJson/Variant/ConverterImpl.hpp b/src/ArduinoJson/Variant/ConverterImpl.hpp
index 5d520acd..cd939595 100644
--- a/src/ArduinoJson/Variant/ConverterImpl.hpp
+++ b/src/ArduinoJson/Variant/ConverterImpl.hpp
@@ -65,8 +65,7 @@ struct Converter<T, detail::enable_if_t<detail::is_integral<T>::value &&
       return false;
     auto resources = getResourceManager(dst);
     data->clear(resources);
-    data->setInteger(src, resources);
-    return true;
+    return data->setInteger(src, resources);
   }
 
   static T fromJson(JsonVariantConst src) {
diff --git a/src/ArduinoJson/Variant/VariantData.hpp b/src/ArduinoJson/Variant/VariantData.hpp
index af49745a..30c5ba0a 100644
--- a/src/ArduinoJson/Variant/VariantData.hpp
+++ b/src/ArduinoJson/Variant/VariantData.hpp
@@ -427,12 +427,12 @@ class VariantData {
   enable_if_t<sizeof(T) == 8, bool> setFloat(T value, ResourceManager*);
 
   template <typename T>
-  enable_if_t<is_signed<T>::value> setInteger(T value,
-                                              ResourceManager* resources);
+  enable_if_t<is_signed<T>::value, bool> setInteger(T value,
+                                                    ResourceManager* resources);
 
   template <typename T>
-  enable_if_t<is_unsigned<T>::value> setInteger(T value,
-                                                ResourceManager* resources);
+  enable_if_t<is_unsigned<T>::value, bool> setInteger(
+      T value, ResourceManager* resources);
 
   void setRawString(StringNode* s) {
     ARDUINOJSON_ASSERT(type_ == VALUE_IS_NULL);  // must call clear() first
diff --git a/src/ArduinoJson/Variant/VariantImpl.hpp b/src/ArduinoJson/Variant/VariantImpl.hpp
index 49dd32e1..11534673 100644
--- a/src/ArduinoJson/Variant/VariantImpl.hpp
+++ b/src/ArduinoJson/Variant/VariantImpl.hpp
@@ -92,7 +92,7 @@ enable_if_t<sizeof(T) == 8, bool> VariantData::setFloat(
 }
 
 template <typename T>
-enable_if_t<is_signed<T>::value> VariantData::setInteger(
+enable_if_t<is_signed<T>::value, bool> VariantData::setInteger(
     T value, ResourceManager* resources) {
   ARDUINOJSON_ASSERT(type_ == VALUE_IS_NULL);  // must call clear() first
   (void)resources;                             // silence warning
@@ -104,17 +104,18 @@ enable_if_t<is_signed<T>::value> VariantData::setInteger(
 #if ARDUINOJSON_USE_LONG_LONG
   else {
     auto extension = resources->allocExtension();
-    if (extension) {
-      type_ = VALUE_IS_INT64;
-      content_.asSlotId = extension.id();
-      extension->asInt64 = value;
-    }
+    if (!extension)
+      return false;
+    type_ = VALUE_IS_INT64;
+    content_.asSlotId = extension.id();
+    extension->asInt64 = value;
   }
 #endif
+  return true;
 }
 
 template <typename T>
-enable_if_t<is_unsigned<T>::value> VariantData::setInteger(
+enable_if_t<is_unsigned<T>::value, bool> VariantData::setInteger(
     T value, ResourceManager* resources) {
   ARDUINOJSON_ASSERT(type_ == VALUE_IS_NULL);  // must call clear() first
   (void)resources;                             // silence warning
@@ -126,13 +127,14 @@ enable_if_t<is_unsigned<T>::value> VariantData::setInteger(
 #if ARDUINOJSON_USE_LONG_LONG
   else {
     auto extension = resources->allocExtension();
-    if (extension) {
-      type_ = VALUE_IS_UINT64;
-      content_.asSlotId = extension.id();
-      extension->asUint64 = value;
-    }
+    if (!extension)
+      return false;
+    type_ = VALUE_IS_UINT64;
+    content_.asSlotId = extension.id();
+    extension->asUint64 = value;
   }
 #endif
+  return true;
 }
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE