diff --git a/include/common_structs.h b/include/common_structs.h
index bb260c216b..0c4c9f881c 100644
--- a/include/common_structs.h
+++ b/include/common_structs.h
@@ -787,7 +787,7 @@ typedef struct EffectInstance {
     /* 0x00 */ s32 flags;
     /* 0x04 */ s32 effectIndex;
     /* 0x08 */ s32 totalMatricies;
-    /* 0x0C */ Vec4f* unk_0C;          // Correct Type?
+    /* 0x0C */ struct EffectInstanceData* data;
     /* 0x10 */ struct Effect* effect;
 } EffectInstance;
 
@@ -804,7 +804,7 @@ typedef struct Effect {
     /* 0x00 */ s32 flags;
     /* 0x04 */ s32 effectIndex;
     /* 0x08 */ s32 instanceCounter;
-    /* 0x0C */ s32 unk_0C;
+    /* 0x0C */ s32 unk_0C;  //? Maybe EffectInstanceData too ?
     /* 0x10 */ void (*update)(EffectInstance* effectInst);
     /* 0x14 */ void (*renderWorld)(EffectInstance* effectInst);
     /* 0x18 */ void (*unk_18)(EffectInstance* effectInst);
@@ -1723,4 +1723,15 @@ typedef struct {
     /* 0x11630 */ Matrix4s matrixStack[0x200];
 } DisplayContext; // size = 0x19630
 
+typedef struct EffectInstanceData {
+    /* 0x00 */ s32 unk_00;
+    /* 0x0C */ Vec3f pos;
+    /* 0x10 */ Vec3f rotation;
+    /* 0x1C */ Vec3f scale;
+    /* 0x28 */ char unk_28[0x4];
+    /* 0x2C */ s32 unk_2C;
+    /* 0x30 */ f32 unk_30;
+    /* 0x34 */ char unk_34[0x4C];
+} EffectInstanceData; // size = 0x80
+
 #endif
diff --git a/src/code_1AF120.c b/src/code_1AF120.c
index c7472eb317..d80703d52c 100644
--- a/src/code_1AF120.c
+++ b/src/code_1AF120.c
@@ -18,10 +18,9 @@ ApiStatus ActorAddMovePos(ScriptInstance* script, s32 isInitialCall) {
     Bytecode* args = script->ptrReadPos;
     EffectInstance* effect = get_variable(script, *args++);
 
-    // TODO: Figure out the actual type of unk_0C
-    effect->unk_0C->y += get_variable(script, *args++);
-    effect->unk_0C->z += get_variable(script, *args++);
-    effect->unk_0C->yaw += get_variable(script, *args++);
+    effect->data->pos.x += get_variable(script, *args++);
+    effect->data->pos.y += get_variable(script, *args++);
+    effect->data->pos.z += get_variable(script, *args++);
 
     return ApiStatus_DONE2;
 }