diff --git a/prover/core/prover.go b/prover/core/prover.go
index c006e2dd23..8f8981394b 100644
--- a/prover/core/prover.go
+++ b/prover/core/prover.go
@@ -42,7 +42,6 @@ func NewProverCore(cfg *config.ProverCoreConfig) (*ProverCore, error) {
 
 	var vk string
 	var rawVK *C.char
-	defer C.free_c_chars(rawVK)
 	if cfg.ProofType == message.ProofTypeBatch {
 		C.init_batch_prover(paramsPathStr, assetsPathStr)
 		rawVK = C.get_batch_vk()
@@ -50,6 +49,7 @@ func NewProverCore(cfg *config.ProverCoreConfig) (*ProverCore, error) {
 		C.init_chunk_prover(paramsPathStr, assetsPathStr)
 		rawVK = C.get_chunk_vk()
 	}
+	defer C.free_c_chars(rawVK)
 
 	if rawVK != nil {
 		vk = C.GoString(rawVK)