diff --git a/app/build.gradle b/app/build.gradle
index cee711d20..927f2e50d 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -127,7 +127,7 @@ configurations.all {
 }
 
 dependencies {
-    implementation "io.github.wulkanowy:sdk:0.21.1"
+    implementation "io.github.wulkanowy:sdk:7577fc9"
 
     coreLibraryDesugaring 'com.android.tools:desugar_jdk_libs:1.0.10'
 
diff --git a/app/src/main/java/io/github/wulkanowy/data/db/adapters/PairAdapterFactory.kt b/app/src/main/java/io/github/wulkanowy/data/db/adapters/PairAdapterFactory.kt
index 60ae37c9d..4a9b168dd 100644
--- a/app/src/main/java/io/github/wulkanowy/data/db/adapters/PairAdapterFactory.kt
+++ b/app/src/main/java/io/github/wulkanowy/data/db/adapters/PairAdapterFactory.kt
@@ -56,11 +56,11 @@ object PairAdapterFactory : JsonAdapter.Factory {
         private fun deserializeGsonPair(reader: JsonReader): List<Pair<String, String>>? {
             val list = listAdapter.fromJson(reader) ?: return null
 
-            require(list.size == 2 || list.isEmpty()) {
-                "pair with more or less than two elements: $list"
-            }
-
             return list.map {
+                require(it.size == 2) {
+                    "pair with more or less than two elements: $list"
+                }
+
                 it["first"].orEmpty() to it["second"].orEmpty()
             }
         }
diff --git a/app/src/test/java/io/github/wulkanowy/data/db/ConvertersTest.kt b/app/src/test/java/io/github/wulkanowy/data/db/ConvertersTest.kt
index 50741b7ab..3b0d7c841 100644
--- a/app/src/test/java/io/github/wulkanowy/data/db/ConvertersTest.kt
+++ b/app/src/test/java/io/github/wulkanowy/data/db/ConvertersTest.kt
@@ -7,19 +7,24 @@ class ConvertersTest {
 
     @Test
     fun stringPairListToJson() {
+        assertEquals(Converters().stringPairListToJson(listOf("aaa" to "bbb", "ccc" to "ddd", "eee" to "fff")), "[{\"first\":\"aaa\",\"second\":\"bbb\"},{\"first\":\"ccc\",\"second\":\"ddd\"},{\"first\":\"eee\",\"second\":\"fff\"}]")
         assertEquals(Converters().stringPairListToJson(listOf("aaa" to "bbb", "ccc" to "ddd")), "[{\"first\":\"aaa\",\"second\":\"bbb\"},{\"first\":\"ccc\",\"second\":\"ddd\"}]")
+        assertEquals(Converters().stringPairListToJson(listOf("aaa" to "bbb")), "[{\"first\":\"aaa\",\"second\":\"bbb\"}]")
         assertEquals(Converters().stringPairListToJson(listOf()), "[]")
     }
 
     @Test
     fun jsonToStringPairList() {
+        assertEquals(Converters().jsonToStringPairList("[{\"first\":\"aaa\",\"second\":\"bbb\"},{\"first\":\"ccc\",\"second\":\"ddd\"},{\"first\":\"eee\",\"second\":\"fff\"}]"), listOf("aaa" to "bbb", "ccc" to "ddd", "eee" to "fff"))
         assertEquals(Converters().jsonToStringPairList("[{\"first\":\"aaa\",\"second\":\"bbb\"},{\"first\":\"ccc\",\"second\":\"ddd\"}]"), listOf("aaa" to "bbb", "ccc" to "ddd"))
+        assertEquals(Converters().jsonToStringPairList("[{\"first\":\"aaa\",\"second\":\"bbb\"}]"), listOf("aaa" to "bbb"))
         assertEquals(Converters().jsonToStringPairList("[]"), listOf<Pair<String, String>>())
     }
 
     @Test
     fun jsonToStringPairList_0210() {
         assertEquals(Converters().jsonToStringPairList("{\"aaa\":\"bbb\",\"ccc\":\"ddd\"}"), listOf("aaa" to "bbb", "ccc" to "ddd"))
+        assertEquals(Converters().jsonToStringPairList("{\"aaa\":\"bbb\"}"), listOf("aaa" to "bbb"))
         assertEquals(Converters().jsonToStringPairList("{}"), listOf<Pair<String, String>>())
     }
 }