diff --git a/libuavcan_drivers/posix/include/uavcan_posix/basic_file_server_backend.hpp b/libuavcan_drivers/posix/include/uavcan_posix/basic_file_server_backend.hpp
index dd501e82fe..e8059b0f89 100644
--- a/libuavcan_drivers/posix/include/uavcan_posix/basic_file_server_backend.hpp
+++ b/libuavcan_drivers/posix/include/uavcan_posix/basic_file_server_backend.hpp
@@ -403,7 +403,7 @@ protected:
                 {
                     rv = 0;
                     ssize_t remaining = inout_size;
-                    ssize_t nread;
+                    ssize_t nread = 0;
                     do
                     {
                         nread = ::read(fd, &out_buffer[total_read], remaining);
diff --git a/libuavcan_drivers/posix/include/uavcan_posix/dynamic_node_id_server/file_event_tracer.hpp b/libuavcan_drivers/posix/include/uavcan_posix/dynamic_node_id_server/file_event_tracer.hpp
index c3328929a7..50b8202184 100644
--- a/libuavcan_drivers/posix/include/uavcan_posix/dynamic_node_id_server/file_event_tracer.hpp
+++ b/libuavcan_drivers/posix/include/uavcan_posix/dynamic_node_id_server/file_event_tracer.hpp
@@ -56,7 +56,7 @@ protected:
                                          static_cast<int>(code), static_cast<long long>(argument));
 
             ssize_t total_written = 0;
-            ssize_t written;
+            ssize_t written = 0;
             do
             {
                 written = write(fd, &buffer[total_written], remaining);
diff --git a/libuavcan_drivers/posix/include/uavcan_posix/dynamic_node_id_server/file_storage_backend.hpp b/libuavcan_drivers/posix/include/uavcan_posix/dynamic_node_id_server/file_storage_backend.hpp
index 664fc7f611..03ee6175bb 100644
--- a/libuavcan_drivers/posix/include/uavcan_posix/dynamic_node_id_server/file_storage_backend.hpp
+++ b/libuavcan_drivers/posix/include/uavcan_posix/dynamic_node_id_server/file_storage_backend.hpp
@@ -57,7 +57,7 @@ protected:
             (void)memset(buffer, 0, sizeof(buffer));
             ssize_t remaining = MaxStringLength;
             ssize_t total_read = 0;
-            ssize_t nread;
+            ssize_t nread = 0;
             do
             {
                 nread = ::read(fd, &buffer[total_read], remaining);
@@ -95,7 +95,7 @@ protected:
         {
             ssize_t remaining = value.size();
             ssize_t total_written = 0;
-            ssize_t written;
+            ssize_t written = 0;
             do
             {
                 written = write(fd, &value.c_str()[total_written], remaining);
diff --git a/libuavcan_drivers/posix/include/uavcan_posix/firmware_version_checker.hpp b/libuavcan_drivers/posix/include/uavcan_posix/firmware_version_checker.hpp
index 7fe66d6ae6..7c6b76cad0 100644
--- a/libuavcan_drivers/posix/include/uavcan_posix/firmware_version_checker.hpp
+++ b/libuavcan_drivers/posix/include/uavcan_posix/firmware_version_checker.hpp
@@ -113,7 +113,7 @@ class FirmwareVersionChecker : public uavcan::IFirmwareVersionChecker
                 }
                 else
                 {
-                    ssize_t size;
+                    ssize_t size = 0;
                     do
                     {
                         size = ::read(sfd, buffer, sizeof(buffer));
@@ -128,7 +128,7 @@ class FirmwareVersionChecker : public uavcan::IFirmwareVersionChecker
                                 rv = 0;
                                 ssize_t remaining = size;
                                 ssize_t total_written = 0;
-                                ssize_t written;
+                                ssize_t written = 0;
                                 do
                                 {
                                     written = write(dfd, &buffer[total_written], remaining);
@@ -146,7 +146,7 @@ class FirmwareVersionChecker : public uavcan::IFirmwareVersionChecker
                             }
                         }
                     }
-                    while (rv == 0 && size);
+                    while (rv == 0 && size != 0);
 
                     (void)close(sfd);
                 }