diff --git a/flake.nix b/flake.nix
index b2df353..a614e1f 100644
--- a/flake.nix
+++ b/flake.nix
@@ -26,6 +26,7 @@
         pkg-config
         clang-tools
         ctags
+        valgrind
       ];
     in
     {
diff --git a/json.c b/json.c
index f3062b3..01b018c 100644
--- a/json.c
+++ b/json.c
@@ -117,7 +117,7 @@ void json_add_long(Json* json, long value)
 void json_add_double(Json* json, double value)
 {
     begin_value(json);
-    fprintf(json->stream, "%f", value);
+    fprintf(json->stream, "%g", value);
     end_value(json);
 }
 
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 39b5967..57380c7 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -7,28 +7,35 @@ FetchContent_Declare(
 )
 FetchContent_MakeAvailable(Unity)
 
-add_executable(
-    json_test
-    json_test.c
-)
-set_target_properties(
-    json_test
-    PROPERTIES
-        C_STANDARD 23
-        C_STANDARD_REQUIRED ON
-        C_EXTENSIONS OFF
-)
-target_link_libraries(
-    json_test
-    PRIVATE
-        json
-        unity::framework
-)
-target_include_directories(
-    json_test
-    PRIVATE
-        ${CMAKE_SOURCE_DIR}
+list(
+    APPEND JSON_TESTS
+        json_tests_simple
+        json_tests_array
 )
+foreach(JSON_TEST IN LISTS JSON_TESTS)
+    add_executable(
+        ${JSON_TEST}
+        ${JSON_TEST}.c
+    )
+    set_target_properties(
+        ${JSON_TEST}
+        PROPERTIES
+            C_STANDARD 23
+            C_STANDARD_REQUIRED ON
+            C_EXTENSIONS OFF
+    )
+    target_link_libraries(
+        ${JSON_TEST}
+        PRIVATE
+            json
+            unity::framework
+    )
+    target_include_directories(
+        ${JSON_TEST}
+        PRIVATE
+            ${CMAKE_SOURCE_DIR}
+    )
 
-add_test(NAME json_test COMMAND json_test)
+    add_test(NAME ${JSON_TEST} COMMAND ${JSON_TEST})
+endforeach()
 
diff --git a/tests/json_test.c b/tests/json_test.c
deleted file mode 100644
index 37cc98f..0000000
--- a/tests/json_test.c
+++ /dev/null
@@ -1,52 +0,0 @@
-#include <stdio.h>
-#include <string.h>
-
-#include <unity.h>
-
-#include <json.h>
-
-static FILE* tmp = nullptr;
-static char buffer[256];
-
-static Json json;
-
-void setUp()
-{
-    tmp = tmpfile();
-    TEST_ASSERT_NOT_NULL(tmp);
-
-    json = json_init(tmp, MINIFIED);
-}
-
-void tearDown()
-{
-    json_free(&json);
-
-    if (tmp) {
-        fclose(tmp);
-        tmp = nullptr;
-    }
-}
-
-void test_json_add_string()
-{
-    json_add_string(&json, "string");
-    fflush(tmp);
-    rewind(tmp);
-
-    char buffer[256];
-    auto n = fread(buffer, 1, sizeof(buffer) - 1, tmp);
-    buffer[n] = '\0';
-
-    TEST_ASSERT_EQUAL_STRING("\"string\"", buffer);
-}
-
-int main()
-{
-    UNITY_BEGIN();
-    {
-        RUN_TEST(test_json_add_string);
-    }
-    return UNITY_END();
-}
-
diff --git a/tests/json_tests_array.c b/tests/json_tests_array.c
new file mode 100644
index 0000000..06c2300
--- /dev/null
+++ b/tests/json_tests_array.c
@@ -0,0 +1,158 @@
+#include <stdio.h>
+#include <string.h>
+
+#include <unity.h>
+
+#include <json.h>
+
+static FILE* tmp = nullptr;
+static char buffer[256];
+
+static Json json;
+
+void setUp()
+{
+    tmp = tmpfile();
+    TEST_ASSERT_NOT_NULL(tmp);
+
+    json = json_init(tmp, MINIFIED);
+}
+
+void tearDown()
+{
+    json_free(&json);
+
+    if (tmp) {
+        fclose(tmp);
+        tmp = nullptr;
+    }
+}
+
+void test_json_array_empty()
+{
+    json_begin_array(&json);
+    json_end_array(&json);
+    fflush(tmp);
+    rewind(tmp);
+
+    auto n = fread(buffer, 1, sizeof(buffer) - 1, tmp);
+    buffer[n] = '\0';
+
+    TEST_ASSERT_EQUAL_STRING("[]", buffer);
+}
+
+void test_json_array_string()
+{
+    json_begin_array(&json);
+    {
+        json_add_string(&json, "string");
+    }
+    json_end_array(&json);
+    fflush(tmp);
+    rewind(tmp);
+
+    auto n = fread(buffer, 1, sizeof(buffer) - 1, tmp);
+    buffer[n] = '\0';
+
+    TEST_ASSERT_EQUAL_STRING("[\"string\"]", buffer);
+}
+
+void test_json_array_long()
+{
+    json_begin_array(&json);
+    {
+        json_add_long(&json, 42);
+    }
+    json_end_array(&json);
+    fflush(tmp);
+    rewind(tmp);
+
+    auto n = fread(buffer, 1, sizeof(buffer) - 1, tmp);
+    buffer[n] = '\0';
+
+    TEST_ASSERT_EQUAL_STRING("[42]", buffer);
+}
+
+void test_json_array_double()
+{
+    json_begin_array(&json);
+    {
+        json_add_double(&json, 3.14);
+    }
+    json_end_array(&json);
+    fflush(tmp);
+    rewind(tmp);
+
+    auto n = fread(buffer, 1, sizeof(buffer) - 1, tmp);
+    buffer[n] = '\0';
+
+    TEST_ASSERT_EQUAL_STRING("[3.14]", buffer);
+}
+
+void test_json_array_bool()
+{
+    json_begin_array(&json);
+    {
+        json_add_bool(&json, true);
+    }
+    json_end_array(&json);
+    fflush(tmp);
+    rewind(tmp);
+
+    auto n = fread(buffer, 1, sizeof(buffer) - 1, tmp);
+    buffer[n] = '\0';
+
+    TEST_ASSERT_EQUAL_STRING("[true]", buffer);
+}
+
+void test_json_array_null()
+{
+    json_begin_array(&json);
+    {
+        json_add_null(&json);
+    }
+    json_end_array(&json);
+    fflush(tmp);
+    rewind(tmp);
+
+    auto n = fread(buffer, 1, sizeof(buffer) - 1, tmp);
+    buffer[n] = '\0';
+
+    TEST_ASSERT_EQUAL_STRING("[null]", buffer);
+}
+
+void test_json_array_mixed()
+{
+    json_begin_array(&json);
+    {
+        json_add_string(&json, "string");
+        json_add_long(&json, 42);
+        json_add_double(&json, 3.14);
+        json_add_bool(&json, true);
+        json_add_null(&json);
+    }
+    json_end_array(&json);
+    fflush(tmp);
+    rewind(tmp);
+
+    auto n = fread(buffer, 1, sizeof(buffer) - 1, tmp);
+    buffer[n] = '\0';
+
+    TEST_ASSERT_EQUAL_STRING("[\"string\",42,3.14,true,null]", buffer);
+}
+
+int main()
+{
+    UNITY_BEGIN();
+    {
+        RUN_TEST(test_json_array_empty);
+        RUN_TEST(test_json_array_string);
+        RUN_TEST(test_json_array_long);
+        RUN_TEST(test_json_array_double);
+        RUN_TEST(test_json_array_bool);
+        RUN_TEST(test_json_array_null);
+        RUN_TEST(test_json_array_mixed);
+    }
+    return UNITY_END();
+}
+
diff --git a/tests/json_tests_simple.c b/tests/json_tests_simple.c
new file mode 100644
index 0000000..b9b1feb
--- /dev/null
+++ b/tests/json_tests_simple.c
@@ -0,0 +1,103 @@
+#include <stdio.h>
+#include <string.h>
+
+#include <unity.h>
+
+#include <json.h>
+
+static FILE* tmp = nullptr;
+static char buffer[256];
+
+static Json json;
+
+void setUp()
+{
+    tmp = tmpfile();
+    TEST_ASSERT_NOT_NULL(tmp);
+
+    json = json_init(tmp, MINIFIED);
+}
+
+void tearDown()
+{
+    json_free(&json);
+
+    if (tmp) {
+        fclose(tmp);
+        tmp = nullptr;
+    }
+}
+
+void test_json_add_string()
+{
+    json_add_string(&json, "string");
+    fflush(tmp);
+    rewind(tmp);
+
+    auto n = fread(buffer, 1, sizeof(buffer) - 1, tmp);
+    buffer[n] = '\0';
+
+    TEST_ASSERT_EQUAL_STRING("\"string\"", buffer);
+}
+
+void test_json_add_long()
+{
+    json_add_long(&json, 42);
+    fflush(tmp);
+    rewind(tmp);
+
+    auto n = fread(buffer, 1, sizeof(buffer) - 1, tmp);
+    buffer[n] = '\0';
+
+    TEST_ASSERT_EQUAL_STRING("42", buffer);
+}
+
+void test_json_add_double()
+{
+    json_add_double(&json, 3.14);
+    fflush(tmp);
+    rewind(tmp);
+
+    auto n = fread(buffer, 1, sizeof(buffer) - 1, tmp);
+    buffer[n] = '\0';
+
+    TEST_ASSERT_EQUAL_STRING("3.14", buffer);
+}
+
+void test_json_add_bool()
+{
+    json_add_bool(&json, true);
+    fflush(tmp);
+    rewind(tmp);
+
+    auto n = fread(buffer, 1, sizeof(buffer) - 1, tmp);
+    buffer[n] = '\0';
+
+    TEST_ASSERT_EQUAL_STRING("true", buffer);
+}
+
+void test_json_add_null()
+{
+    json_add_null(&json);
+    fflush(tmp);
+    rewind(tmp);
+
+    auto n = fread(buffer, 1, sizeof(buffer) - 1, tmp);
+    buffer[n] = '\0';
+
+    TEST_ASSERT_EQUAL_STRING("null", buffer);
+}
+
+int main()
+{
+    UNITY_BEGIN();
+    {
+        RUN_TEST(test_json_add_string);
+        RUN_TEST(test_json_add_long);
+        RUN_TEST(test_json_add_double);
+        RUN_TEST(test_json_add_bool);
+        RUN_TEST(test_json_add_null);
+    }
+    return UNITY_END();
+}
+