diff --git a/lib/zip_crypto_openssl.c b/lib/zip_crypto_openssl.c
index 3b45fe9e4..f7b910a60 100644
--- a/lib/zip_crypto_openssl.c
+++ b/lib/zip_crypto_openssl.c
@@ -126,7 +126,7 @@ _zip_crypto_aes_free(_zip_crypto_aes_t *aes) {
 
 bool
 _zip_crypto_aes_encrypt_block(_zip_crypto_aes_t *aes, const zip_uint8_t *in, zip_uint8_t *out) {
-    int len;
+    int len = 0;
     if (EVP_EncryptUpdate(aes, out, &len, in, ZIP_CRYPTO_AES_BLOCK_LENGTH) != 1
         || len != ZIP_CRYPTO_AES_BLOCK_LENGTH) {
         return false;
@@ -215,10 +215,10 @@ _zip_crypto_hmac_free(_zip_crypto_hmac_t *hmac) {
 bool
 _zip_crypto_hmac_output(_zip_crypto_hmac_t *hmac, zip_uint8_t *data) {
 #ifdef USE_OPENSSL_3_API
-    size_t length;
+    size_t length = 0;
     return EVP_MAC_final(hmac->ctx, data, &length, ZIP_CRYPTO_SHA1_LENGTH) == 1 && length == ZIP_CRYPTO_SHA1_LENGTH;
 #else
-    unsigned int length;
+    unsigned int length = 0;
     return HMAC_Final(hmac, data, &length) == 1 && length == ZIP_CRYPTO_SHA1_LENGTH;
 #endif
 }