diff --git a/DESCRIPTION b/DESCRIPTION
index d7b88f6..97ed55f 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -23,4 +23,4 @@ URL: https://shikokuchuo.net/secretbase/,
 Encoding: UTF-8
 Depends: 
     R (>= 3.5)
-RoxygenNote: 7.3.1
+RoxygenNote: 7.3.2
diff --git a/src/base.c b/src/base.c
index 4a7c439..f7d1fbf 100644
--- a/src/base.c
+++ b/src/base.c
@@ -361,8 +361,9 @@ static nano_buf nano_any_buf(const SEXP x) {
 
 SEXP secretbase_base64enc(SEXP x, SEXP convert) {
   
-  int xc, conv;
-  SB_LOGICAL(conv, convert);
+  SB_ASSERT_LOGICAL(convert);
+  const int conv = SB_LOGICAL(convert);
+  int xc;
   SEXP out;
   size_t olen;
   
@@ -371,7 +372,7 @@ SEXP secretbase_base64enc(SEXP x, SEXP convert) {
   unsigned char *buf = R_Calloc(olen, unsigned char);
   xc = mbedtls_base64_encode(buf, olen, &olen, hash.buf, hash.cur);
   NANO_FREE(hash);
-  CHECK_ERROR(xc, buf);
+  CHECK_ERROR(xc);
   
   if (conv) {
     out = rawToChar(buf, olen);
@@ -388,8 +389,9 @@ SEXP secretbase_base64enc(SEXP x, SEXP convert) {
 
 SEXP secretbase_base64dec(SEXP x, SEXP convert) {
   
-  int xc, conv;
-  SB_LOGICAL(conv, convert);
+  SB_ASSERT_LOGICAL(convert);
+  const int conv = SB_LOGICAL(convert);
+  int xc;
   unsigned char *inbuf;
   SEXP out;
   size_t inlen, olen;
@@ -412,7 +414,7 @@ SEXP secretbase_base64dec(SEXP x, SEXP convert) {
     Rf_error("input is not valid base64");
   unsigned char *buf = R_Calloc(olen, unsigned char);
   xc = mbedtls_base64_decode(buf, olen, &olen, inbuf, inlen);
-  CHECK_ERROR(xc, buf);
+  CHECK_ERROR(xc);
   
   switch (conv) {
   case 0:
diff --git a/src/secret.c b/src/secret.c
index 1dbbe67..33203d8 100644
--- a/src/secret.c
+++ b/src/secret.c
@@ -249,7 +249,7 @@ static inline void hash_bytes(R_outpstream_t stream, void *src, int len) {
 
 static void hash_file(mbedtls_sha3_context *ctx, const SEXP x) {
   
-  SB_CHK_STR(x);
+  SB_ASSERT_STR(x);
   const char *file = R_ExpandFileName(SB_STRING(x));
   unsigned char buf[SB_BUF_SIZE];
   FILE *f;
@@ -336,8 +336,8 @@ static SEXP secretbase_sha3_impl(const SEXP x, const SEXP bits, const SEXP conve
                                  void (*const hash_func)(mbedtls_sha3_context *, SEXP),
                                  const int offset) {
   
-  int conv;
-  SB_LOGICAL(conv, convert);
+  SB_ASSERT_LOGICAL(convert);
+  const int conv = SB_LOGICAL(convert);
   const int bt = nano_integer(bits);
   mbedtls_sha3_id id;
   
diff --git a/src/secret.h b/src/secret.h
index db254cb..9a5107b 100644
--- a/src/secret.h
+++ b/src/secret.h
@@ -28,9 +28,10 @@
 
 #define SB_DATAPTR(x) (void *) DATAPTR_RO(x)
 #define SB_STRING(x) CHAR(*((const SEXP *) DATAPTR_RO(x)))
-#define SB_LOGICAL(v, x) if (TYPEOF(x) != LGLSXP)              \
-Rf_error("'convert' must be a logical value"); else v = *(int *) DATAPTR_RO(x)
-#define SB_CHK_STR(x) if (TYPEOF(x) != STRSXP)                 \
+#define SB_LOGICAL(x) *(int *) DATAPTR_RO(x)
+#define SB_ASSERT_LOGICAL(x) if (TYPEOF(x) != LGLSXP)          \
+Rf_error("'convert' must be a logical value")
+#define SB_ASSERT_STR(x) if (TYPEOF(x) != STRSXP)              \
 Rf_error("'file' must be a character string")
 
 #define SB_R_SERIAL_VER 3
@@ -114,7 +115,7 @@ typedef struct nano_buf_s {
 (x)->len = 0;                                                  \
 (x)->cur = sz
 #define NANO_FREE(x) if (x.len) R_Free(x.buf)
-#define CHECK_ERROR(x, buf) if (x) { R_Free(buf);              \
+#define CHECK_ERROR(x) if (x) { R_Free(buf);                   \
 Rf_error("write buffer insufficient"); }
 #define ERROR_OUT(x) if (x->len) R_Free(x->buf);               \
 Rf_error("serialization exceeds max length of raw vector")
diff --git a/src/secret2.c b/src/secret2.c
index d06ec54..c96f101 100644
--- a/src/secret2.c
+++ b/src/secret2.c
@@ -384,7 +384,7 @@ static inline void hash_bytes(R_outpstream_t stream, void *src, int len) {
 
 static void hash_file(mbedtls_sha256_context *ctx, const SEXP x) {
   
-  SB_CHK_STR(x);
+  SB_ASSERT_STR(x);
   const char *file = R_ExpandFileName(SB_STRING(x));
   unsigned char buf[SB_BUF_SIZE];
   FILE *f;
@@ -447,8 +447,8 @@ static void hash_object(mbedtls_sha256_context *ctx, const SEXP x) {
 static SEXP secretbase_sha256_impl(const SEXP x, const SEXP key, const SEXP convert,
                                    void (*const hash_func)(mbedtls_sha256_context *, SEXP)) {
   
-  int conv;
-  SB_LOGICAL(conv, convert);
+  SB_ASSERT_LOGICAL(convert);
+  const int conv = SB_LOGICAL(convert);
   unsigned char buf[SB_SHA256_SIZE];
   
   if (key == R_NilValue) {
diff --git a/src/secret3.c b/src/secret3.c
index a8c3a80..410f69b 100644
--- a/src/secret3.c
+++ b/src/secret3.c
@@ -191,7 +191,7 @@ static inline void hash_bytes(R_outpstream_t stream, void *src, int len) {
 
 static void hash_file(CSipHash *ctx, const SEXP x) {
   
-  SB_CHK_STR(x);
+  SB_ASSERT_STR(x);
   const char *file = R_ExpandFileName(SB_STRING(x));
   unsigned char buf[SB_BUF_SIZE];
   FILE *f;
@@ -252,8 +252,8 @@ static void hash_object(CSipHash *ctx, const SEXP x) {
 static SEXP secretbase_siphash_impl(const SEXP x, const SEXP key, const SEXP convert,
                                     void (*const hash_func)(CSipHash *, SEXP)) {
   
-  int conv;
-  SB_LOGICAL(conv, convert);
+  SB_ASSERT_LOGICAL(convert);
+  const int conv = SB_LOGICAL(convert);
   uint64_t hash;
   
   CSipHash ctx;