diff --git a/src/shared/data.c b/src/shared/data.c
index e0e3156..82e6198 100644
--- a/src/shared/data.c
+++ b/src/shared/data.c
@@ -1,6 +1,6 @@
 #include "data.h"
 #include "log.h"
-#include "stdlib.h"
+#include <stdlib.h>
 
 Data* data_create_empty(size_t data_size) {
   /* malloc(0) is UB; allocate at least 1 byte but preserve requested size */
diff --git a/src/shared/protocol.c b/src/shared/protocol.c
index f07b8a1..1e5cb7f 100644
--- a/src/shared/protocol.c
+++ b/src/shared/protocol.c
@@ -34,14 +34,11 @@ static void bw_throttle(size_t bytes_written) {
   struct timespec now;
   clock_gettime(CLOCK_MONOTONIC, &now);
 
-  /* Use unsigned long long for elapsed_ns to avoid overflow in multiplication.
-   * time_t differences fit comfortably in 64-bit for any practical runtime. */
-  unsigned long long elapsed_ns =
-      (unsigned long long)(now.tv_sec - bw_last_refill.tv_sec) * 1000000000ULL +
-      (unsigned long long)(now.tv_nsec - bw_last_refill.tv_nsec);
+  long long elapsed_ns =
+      (now.tv_sec - bw_last_refill.tv_sec) * 1000000000LL + (now.tv_nsec - bw_last_refill.tv_nsec);
   bw_last_refill = now;
 
-  long long tokens_to_add = (long long)((double)io_bwlimit * (double)elapsed_ns / 1000000000.0);
+  long long tokens_to_add = (long long)((double)io_bwlimit * elapsed_ns / 1000000000.0);
   bw_tokens += tokens_to_add;
   if (bw_tokens > (long long)io_bwlimit)
     bw_tokens = (long long)io_bwlimit;
@@ -49,9 +46,7 @@ static void bw_throttle(size_t bytes_written) {
   bw_tokens -= (long long)bytes_written;
 
   if (bw_tokens < 0) {
-    long long deficit_ns = (long long)((double)(-bw_tokens) / (double)io_bwlimit * 1000000000.0);
-    if (deficit_ns < 0)
-      deficit_ns = 0;
+    long long deficit_ns = (long long)((double)(-bw_tokens) / io_bwlimit * 1000000000.0);
     struct timespec sleep_time, remaining;
     sleep_time.tv_sec = deficit_ns / 1000000000LL;
     sleep_time.tv_nsec = deficit_ns % 1000000000LL;
@@ -84,11 +79,6 @@ bool send_n_data(int file_descriptor, const void* data, size_t data_size) {
     else
       bytes_send = write(fd, (const char*)data + total_bytes_send, chunk);
     if (bytes_send <= 0) {
-      if (io_ssl) {
-        int ssl_err = SSL_get_error(io_ssl, (int)bytes_send);
-        if (ssl_err == SSL_ERROR_WANT_WRITE || ssl_err == SSL_ERROR_WANT_READ)
-          continue;
-      }
       log_message(LOG_LEVEL_ERROR, "Could not send data");
       return false;
     }
@@ -112,11 +102,6 @@ bool receive_n_data(int file_descriptor, void* data, size_t data_size) {
       bytes_received =
           read(fd, (char*)data + total_bytes_received, data_size - total_bytes_received);
     if (bytes_received <= 0) {
-      if (io_ssl) {
-        int ssl_err = SSL_get_error(io_ssl, (int)bytes_received);
-        if (ssl_err == SSL_ERROR_WANT_READ || ssl_err == SSL_ERROR_WANT_WRITE)
-          continue;
-      }
       if (bytes_received == 0)
         log_message(LOG_LEVEL_ERROR, "Connection closed while receiving data");
       else
@@ -193,18 +178,18 @@ bool send_data(int file_descriptor, const Data* data) {
     return false;
   if (!send_n_data(file_descriptor, data->data, data_size))
     return false;
-  log_message(LOG_LEVEL_DEBUG, "Send %lld data", data_size);
+  log_message(LOG_LEVEL_DEBUG, "Send %llu data", data_size);
   return true;
 }
 
-#define MAX_DATA_SIZE (1024ULL * 1024 * 1024) // 1 GB
+#define MAX_DATA_SIZE (1024ULL * 1024 * 1024)
 
 Data* receive_data(int file_descriptor) {
   unsigned long long size = 0;
   if (!receive_n_data(file_descriptor, &size, sizeof(unsigned long long)))
     return NULL;
-  if (size > MAX_DATA_SIZE) {
-    log_message(LOG_LEVEL_ERROR, "receive_data: size %llu exceeds maximum", size);
+  if ((size_t)size != size || size > MAX_DATA_SIZE) {
+    log_message(LOG_LEVEL_ERROR, "receive_data size %llu exceeds limits", size);
     return NULL;
   }
   void* data = malloc((size_t)size);
@@ -214,7 +199,7 @@ Data* receive_data(int file_descriptor) {
     free(data);
     return NULL;
   }
-  log_message(LOG_LEVEL_DEBUG, "Received %lld data", size);
+  log_message(LOG_LEVEL_DEBUG, "Received %llu data", size);
   return data_create(data, (size_t)size);
 }
 
diff --git a/src/shared/utils.c b/src/shared/utils.c
index 680a6b2..a5b67cd 100644
--- a/src/shared/utils.c
+++ b/src/shared/utils.c
@@ -134,7 +134,7 @@ static void delete_extras_walk(const char* abs_path, const char* rel_path, Array
   if (!dir)
     return;
   bool all_removed = true;
-  struct dirent* entry;
+  const struct dirent* entry;
   while ((entry = readdir(dir)) != NULL) {
     if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
       continue;
@@ -184,18 +184,17 @@ void delete_extras(const char* dest_root, ArrayList* manifest) {
   delete_extras_walk(dest_root, "", manifest);
 }
 
-char* path_cat(const char* path1, char* path2) {
+char* path_cat(const char* path1, const char* path2) {
   if (path1 == NULL || *path1 == '\0')
     return str_dup(path2);
   if (path2 == NULL || *path2 == '\0')
     return str_dup(path1);
   int path1_len = strlen(path1);
   int path2_len = strlen(path2);
-  char* path2_pointer = path2;
   if (path1[path1_len - 1] == '/')
     path1_len -= 1;
   if (path2[0] == '/') {
-    path2_pointer += 1;
+    path2++;
     path2_len -= 1;
   }
   char* new_path = malloc(path1_len + path2_len + 2);
@@ -203,7 +202,7 @@ char* path_cat(const char* path1, char* path2) {
     return NULL;
   memcpy(new_path, path1, path1_len);
   new_path[path1_len] = '/';
-  memcpy(new_path + path1_len + 1, path2_pointer, path2_len);
+  memcpy(new_path + path1_len + 1, path2, path2_len);
   new_path[path1_len + path2_len + 1] = '\0';
   return new_path;
 }
diff --git a/src/shared/utils.h b/src/shared/utils.h
index 13cd999..1cc8a6c 100644
--- a/src/shared/utils.h
+++ b/src/shared/utils.h
@@ -6,7 +6,7 @@
 
 bool mkdir_r(const char* path);
 char* str_dup(const char* string);
-char* path_cat(const char* path1, char* path2);
+char* path_cat(const char* path1, const char* path2);
 bool glob_match(const char* pattern, const char* str);
 void delete_extras(const char* dest_root, ArrayList* manifest);
 
diff --git a/tests/test_protocol.c b/tests/test_protocol.c
index f644032..bece803 100644
--- a/tests/test_protocol.c
+++ b/tests/test_protocol.c
@@ -179,8 +179,7 @@ static void test_receive_str_oversized() {
   size_t huge = MAX_STRING_SIZE + 1;
   EXPECT_TRUE(send_n_data(0, &huge, sizeof(size_t)));
 
-  /* cppcheck-suppress constVariablePointer */
-  char* received = receive_str(0);
+  const char* received = receive_str(0);
   EXPECT_NULL(received);
 
   close(p[0]);