diff --git a/include/groundvm.h b/include/groundvm.h
index 13c8fc1..c10158f 100644
--- a/include/groundvm.h
+++ b/include/groundvm.h
@@ -60,7 +60,7 @@ typedef struct GroundError {
 typedef struct GroundValue {
     GroundValueType type;
     struct GroundStruct* customType;
-    union {
+    struct {
         int64_t intVal;
         double doubleVal;
         char* stringVal;
diff --git a/src/types.h b/src/types.h
index 1639cd2..a288cc8 100644
--- a/src/types.h
+++ b/src/types.h
@@ -62,7 +62,8 @@ typedef struct GroundError {
  */
 typedef struct GroundValue {
     GroundValueType type;
-    union {
+    struct GroundStruct* customType;
+    struct {
         int64_t intVal;
         double doubleVal;
         char* stringVal;
@@ -74,7 +75,6 @@ typedef struct GroundValue {
         struct GroundStruct* structVal;
         struct GroundObject* customVal;
     } data;
-    struct GroundStruct* customType;
 } GroundValue;
 
 /*