diff --git a/identity/Util.cpp b/identity/Util.cpp
index c397913..70e7105 100644
--- a/identity/Util.cpp
+++ b/identity/Util.cpp
@@ -60,7 +60,7 @@
     uint8_t* p = data.data();
     size_t remaining = data.size();
     while (remaining > 0) {
-        size_t numRead = TEMP_FAILURE_RETRY(read(fd, p, remaining));
+        ssize_t numRead = TEMP_FAILURE_RETRY(read(fd, p, remaining));
         if (numRead <= 0) {
             PLOG(ERROR) << "Failed reading from '" << path << "'";
             close(fd);
@@ -94,7 +94,7 @@
     const uint8_t* p = data.data();
     size_t remaining = data.size();
     while (remaining > 0) {
-        size_t numWritten = TEMP_FAILURE_RETRY(write(fd, p, remaining));
+        ssize_t numWritten = TEMP_FAILURE_RETRY(write(fd, p, remaining));
         if (numWritten <= 0) {
             PLOG(ERROR) << "Failed writing into temp file for '" << path << "'";
             close(fd);