diff --git a/selfdrive/common/util.cc b/selfdrive/common/util.cc
index 40f6566969..63e3f6fa00 100644
--- a/selfdrive/common/util.cc
+++ b/selfdrive/common/util.cc
@@ -194,22 +194,13 @@ float getenv(const char* key, float default_val) {
   return val ? atof(val) : default_val;
 }
 
-std::string tohex(const uint8_t *buf, size_t buf_size) {
-  std::unique_ptr<char[]> hexbuf(new char[buf_size * 2 + 1]);
-  for (size_t i = 0; i < buf_size; i++) {
-    sprintf(&hexbuf[i * 2], "%02x", buf[i]);
+std::string hexdump(const uint8_t* in, const size_t size) {
+  std::stringstream ss;
+  ss << std::hex << std::setfill('0');
+  for (size_t i = 0; i < size; i++) {
+    ss << std::setw(2) << static_cast<unsigned int>(in[i]);
   }
-  hexbuf[buf_size * 2] = 0;
-  return std::string(hexbuf.get(), hexbuf.get() + buf_size * 2);
-}
-
-std::string hexdump(const std::string& in) {
-    std::stringstream ss;
-    ss << std::hex << std::setfill('0');
-    for (size_t i = 0; i < in.size(); i++) {
-        ss << std::setw(2) << static_cast<unsigned int>(static_cast<unsigned char>(in[i]));
-    }
-    return ss.str();
+  return ss.str();
 }
 
 std::string dir_name(std::string const &path) {
diff --git a/selfdrive/common/util.h b/selfdrive/common/util.h
index aacb7af3b9..4f6d4fa19b 100644
--- a/selfdrive/common/util.h
+++ b/selfdrive/common/util.h
@@ -66,8 +66,7 @@ std::string getenv(const char* key, const char* default_val = "");
 int getenv(const char* key, int default_val);
 float getenv(const char* key, float default_val);
 
-std::string tohex(const uint8_t* buf, size_t buf_size);
-std::string hexdump(const std::string& in);
+std::string hexdump(const uint8_t* in, const size_t size);
 std::string dir_name(std::string const& path);
 
 // **** file fhelpers *****
diff --git a/selfdrive/modeld/thneed/thneed.cc b/selfdrive/modeld/thneed/thneed.cc
index 242905d9f4..a3588f1d1f 100644
--- a/selfdrive/modeld/thneed/thneed.cc
+++ b/selfdrive/modeld/thneed/thneed.cc
@@ -11,7 +11,7 @@
 
 #include "selfdrive/common/clutil.h"
 #include "selfdrive/common/timing.h"
-
+#include "selfdrive/common/util.h"
 //#define RUN_DISASSEMBLER
 //#define RUN_OPTIMIZER
 
@@ -21,14 +21,10 @@ map<pair<cl_kernel, int>, string> g_args;
 map<pair<cl_kernel, int>, int> g_args_size;
 map<cl_program, string> g_program_source;
 
-void hexdump(uint32_t *d, int len) {
+void hexdump(uint8_t *d, int len) {
   assert((len%4) == 0);
   printf("  dumping %p len 0x%x\n", d, len);
-  for (int i = 0; i < len/4; i++) {
-    if (i != 0 && (i%0x10) == 0) printf("\n");
-    printf("%8x ", d[i]);
-  }
-  printf("\n");
+  printf("%s\n", util::hexdump(d, len).c_str());
 }
 
 // *********** ioctl interceptor ***********
@@ -94,10 +90,10 @@ int ioctl(int filedes, unsigned long request, void *argp) {
         struct kgsl_device_getproperty *prop = (struct kgsl_device_getproperty *)argp;
         printf("IOCTL_KGSL_SETPROPERTY: 0x%x sizebytes:%zu\n", prop->type, prop->sizebytes);
         if (thneed->record & THNEED_VERBOSE_DEBUG) {
-          hexdump((uint32_t *)prop->value, prop->sizebytes);
+          hexdump((uint8_t *)prop->value, prop->sizebytes);
           if (prop->type == KGSL_PROP_PWR_CONSTRAINT) {
             struct kgsl_device_constraint *constraint = (struct kgsl_device_constraint *)prop->value;
-            hexdump((uint32_t *)constraint->data, constraint->size);
+            hexdump((uint8_t *)constraint->data, constraint->size);
           }
         }
       }
diff --git a/selfdrive/ui/replay/util.cc b/selfdrive/ui/replay/util.cc
index 0560571474..b4fcbf7e6b 100644
--- a/selfdrive/ui/replay/util.cc
+++ b/selfdrive/ui/replay/util.cc
@@ -9,7 +9,6 @@
 #include <iostream>
 #include <mutex>
 #include <numeric>
-#include <sstream>
 
 #include "selfdrive/common/timing.h"
 #include "selfdrive/common/util.h"
@@ -216,9 +215,5 @@ std::string sha256(const std::string &str) {
   SHA256_Init(&sha256);
   SHA256_Update(&sha256, str.c_str(), str.size());
   SHA256_Final(hash, &sha256);
-  std::stringstream ss;
-  for (int i = 0; i < SHA256_DIGEST_LENGTH; i++) {
-    ss << std::hex << std::setw(2) << std::setfill('0') << (int)hash[i];
-  }
-  return ss.str();
+  return util::hexdump(hash, SHA256_DIGEST_LENGTH);
 }