diff --git a/src/core/ngx_string.c b/src/core/ngx_string.c
index 468e960..93f32ea 100644
--- a/src/core/ngx_string.c
+++ b/src/core/ngx_string.c
@@ -11,6 +11,8 @@
 
 static u_char *ngx_sprintf_num(u_char *buf, u_char *last, uint64_t ui64,
     u_char zero, ngx_uint_t hexadecimal, ngx_uint_t width);
+static u_char *ngx_sprintf_str(u_char *buf, u_char *last, u_char *src,
+    size_t len, ngx_uint_t hexadecimal);
 static void ngx_encode_base64_internal(ngx_str_t *dst, ngx_str_t *src,
     const u_char *basis, ngx_uint_t padding);
 static ngx_int_t ngx_decode_base64_internal(ngx_str_t *dst, ngx_str_t *src,
@@ -101,10 +103,10 @@
  *    %M                        ngx_msec_t
  *    %r                        rlim_t
  *    %p                        void *
- *    %V                        ngx_str_t *
- *    %v                        ngx_variable_value_t *
- *    %s                        null-terminated string
- *    %*s                       length and string
+ *    %[x|X]V                   ngx_str_t *
+ *    %[x|X]v                   ngx_variable_value_t *
+ *    %[x|X]s                   null-terminated string
+ *    %*[x|X]s                  length and string
  *    %Z                        '\0'
  *    %N                        '\n'
  *    %c                        char
@@ -165,7 +167,7 @@
     u_char                *p, zero;
     int                    d;
     double                 f;
-    size_t                 len, slen;
+    size_t                 slen;
     int64_t                i64;
     uint64_t               ui64, frac;
     ngx_msec_t             ms;
@@ -250,8 +252,7 @@
             case 'V':
                 v = va_arg(args, ngx_str_t *);
 
-                len = ngx_min(((size_t) (last - buf)), v->len);
-                buf = ngx_cpymem(buf, v->data, len);
+                buf = ngx_sprintf_str(buf, last, v->data, v->len, hex);
                 fmt++;
 
                 continue;
@@ -259,8 +260,7 @@
             case 'v':
                 vv = va_arg(args, ngx_variable_value_t *);
 
-                len = ngx_min(((size_t) (last - buf)), vv->len);
-                buf = ngx_cpymem(buf, vv->data, len);
+                buf = ngx_sprintf_str(buf, last, vv->data, vv->len, hex);
                 fmt++;
 
                 continue;
@@ -268,16 +268,7 @@
             case 's':
                 p = va_arg(args, u_char *);
 
-                if (slen == (size_t) -1) {
-                    while (*p && buf < last) {
-                        *buf++ = *p++;
-                    }
-
-                } else {
-                    len = ngx_min(((size_t) (last - buf)), slen);
-                    buf = ngx_cpymem(buf, p, len);
-                }
-
+                buf = ngx_sprintf_str(buf, last, p, slen, hex);
                 fmt++;
 
                 continue;
@@ -576,6 +567,64 @@
 }
 
 
+static u_char *
+ngx_sprintf_str(u_char *buf, u_char *last, u_char *src, size_t len,
+    ngx_uint_t hexadecimal)
+{
+    static u_char   hex[] = "0123456789abcdef";
+    static u_char   HEX[] = "0123456789ABCDEF";
+
+    if (hexadecimal == 0) {
+
+        if (len == (size_t) -1) {
+            while (*src && buf < last) {
+                *buf++ = *src++;
+            }
+
+        } else {
+            len = ngx_min((size_t) (last - buf), len);
+            buf = ngx_cpymem(buf, src, len);
+        }
+
+    } else if (hexadecimal == 1) {
+
+        if (len == (size_t) -1) {
+
+            while (*src && buf < last - 1) {
+                *buf++ = hex[*src >> 4];
+                *buf++ = hex[*src++ & 0xf];
+            }
+
+        } else {
+
+            while (len-- && buf < last - 1) {
+                *buf++ = hex[*src >> 4];
+                *buf++ = hex[*src++ & 0xf];
+            }
+        }
+
+    } else { /* hexadecimal == 2 */
+
+        if (len == (size_t) -1) {
+
+            while (*src && buf < last - 1) {
+                *buf++ = HEX[*src >> 4];
+                *buf++ = HEX[*src++ & 0xf];
+            }
+
+        } else {
+
+            while (len-- && buf < last - 1) {
+                *buf++ = HEX[*src >> 4];
+                *buf++ = HEX[*src++ & 0xf];
+            }
+        }
+    }
+
+    return buf;
+}
+
+
 /*
  * We use ngx_strcasecmp()/ngx_strncasecmp() for 7-bit ASCII strings only,
  * and implement our own ngx_strcasecmp()/ngx_strncasecmp()
diff --git a/src/event/ngx_event_openssl.c b/src/event/ngx_event_openssl.c
index 2eef87e..fd2b92f 100644
--- a/src/event/ngx_event_openssl.c
+++ b/src/event/ngx_event_openssl.c
@@ -4057,9 +4057,6 @@
     ngx_ssl_session_ticket_key_t  *key;
     const EVP_MD                  *digest;
     const EVP_CIPHER              *cipher;
-#if (NGX_DEBUG)
-    u_char                         buf[32];
-#endif
 
     c = ngx_ssl_get_connection(ssl_conn);
     ssl_ctx = c->ssl->session_ctx;
@@ -4081,8 +4078,8 @@
         /* encrypt session ticket */
 
         ngx_log_debug3(NGX_LOG_DEBUG_EVENT, c->log, 0,
-                       "ssl session ticket encrypt, key: \"%*s\" (%s session)",
-                       ngx_hex_dump(buf, key[0].name, 16) - buf, buf,
+                       "ssl session ticket encrypt, key: \"%*xs\" (%s session)",
+                       (size_t) 16, key[0].name,
                        SSL_session_reused(ssl_conn) ? "reused" : "new");
 
         if (key[0].size == 48) {
@@ -4128,17 +4125,16 @@
         }
 
         ngx_log_debug2(NGX_LOG_DEBUG_EVENT, c->log, 0,
-                       "ssl session ticket decrypt, key: \"%*s\" not found",
-                       ngx_hex_dump(buf, name, 16) - buf, buf);
+                       "ssl session ticket decrypt, key: \"%*xs\" not found",
+                       (size_t) 16, name);
 
         return 0;
 
     found:
 
         ngx_log_debug3(NGX_LOG_DEBUG_EVENT, c->log, 0,
-                       "ssl session ticket decrypt, key: \"%*s\"%s",
-                       ngx_hex_dump(buf, key[i].name, 16) - buf, buf,
-                       (i == 0) ? " (default)" : "");
+                       "ssl session ticket decrypt, key: \"%*xs\"%s",
+                       (size_t) 16, key[i].name, (i == 0) ? " (default)" : "");
 
         if (key[i].size == 48) {
             cipher = EVP_aes_128_cbc();
diff --git a/src/event/ngx_event_openssl_stapling.c b/src/event/ngx_event_openssl_stapling.c
index 9d92421..e3fa8c4 100644
--- a/src/event/ngx_event_openssl_stapling.c
+++ b/src/event/ngx_event_openssl_stapling.c
@@ -2662,16 +2662,8 @@
     p = ngx_cpymem(p, serial->data, serial->length);
     ngx_memzero(p, 20 - serial->length);
 
-#if (NGX_DEBUG)
-    {
-        u_char  buf[120];
-
-        ngx_hex_dump(buf, ctx->key.data, ctx->key.len);
-
-        ngx_log_debug2(NGX_LOG_DEBUG_EVENT, ctx->log, 0,
-                       "ssl ocsp key %*s", sizeof(buf), buf);
-    }
-#endif
+    ngx_log_debug1(NGX_LOG_DEBUG_EVENT, ctx->log, 0,
+                   "ssl ocsp key %xV", &ctx->key);
 
     return NGX_OK;
 }
diff --git a/src/http/modules/ngx_http_grpc_module.c b/src/http/modules/ngx_http_grpc_module.c
index 7e14af8..0b8bb52 100644
--- a/src/http/modules/ngx_http_grpc_module.c
+++ b/src/http/modules/ngx_http_grpc_module.c
@@ -1141,20 +1141,11 @@
 
     f->flags |= NGX_HTTP_V2_END_HEADERS_FLAG;
 
-#if (NGX_DEBUG)
-    if (r->connection->log->log_level & NGX_LOG_DEBUG_HTTP) {
-        u_char  buf[512];
-        size_t  n, m;
-
-        n = ngx_min(b->last - b->pos, 256);
-        m = ngx_hex_dump(buf, b->pos, n) - buf;
-
-        ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
-                       "grpc header: %*s%s, len: %uz",
-                       m, buf, b->last - b->pos > 256 ? "..." : "",
-                       b->last - b->pos);
-    }
-#endif
+    ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "grpc header: %*xs%s, len: %uz",
+                   (size_t) ngx_min(b->last - b->pos, 256), b->pos,
+                   b->last - b->pos > 256 ? "..." : "",
+                   b->last - b->pos);
 
     if (r->request_body_no_buffering) {
 
@@ -1604,20 +1595,11 @@
     u = r->upstream;
     b = &u->buffer;
 
-#if (NGX_DEBUG)
-    if (r->connection->log->log_level & NGX_LOG_DEBUG_HTTP) {
-        u_char  buf[512];
-        size_t  n, m;
-
-        n = ngx_min(b->last - b->pos, 256);
-        m = ngx_hex_dump(buf, b->pos, n) - buf;
-
-        ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
-                       "grpc response: %*s%s, len: %uz",
-                       m, buf, b->last - b->pos > 256 ? "..." : "",
-                       b->last - b->pos);
-    }
-#endif
+    ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "grpc response: %*xs%s, len: %uz",
+                   (size_t) ngx_min(b->last - b->pos, 256),
+                   b->pos, b->last - b->pos > 256 ? "..." : "",
+                   b->last - b->pos);
 
     ctx = ngx_http_grpc_get_ctx(r);