diff --git a/src/add-ons/kernel/drivers/tty/tty.cpp b/src/add-ons/kernel/drivers/tty/tty.cpp
index 4cc10d1ee4..02b713daf3 100644
--- a/src/add-ons/kernel/drivers/tty/tty.cpp
+++ b/src/add-ons/kernel/drivers/tty/tty.cpp
@@ -1348,7 +1348,7 @@ tty_write_to_tty_master_unsafe(tty_cookie* sourceCookie, const char* data,
 		// If in echo mode, we do the output conversion and need to update
 		// the needed bytes count.
 		char echoBuffer[3];
-		size_t echoBytes;
+		size_t echoBytes = 0;
 		if (echo) {
 			process_output_char(source, c, echoBuffer, &echoBytes, true);
 			if (echoBytes > bytesNeeded)
diff --git a/src/add-ons/kernel/generic/tty/tty.cpp b/src/add-ons/kernel/generic/tty/tty.cpp
index 2d8cc68759..7d978e23b6 100644
--- a/src/add-ons/kernel/generic/tty/tty.cpp
+++ b/src/add-ons/kernel/generic/tty/tty.cpp
@@ -1062,7 +1062,7 @@ tty_write_to_tty_master_unsafe(tty_cookie* sourceCookie, const char* data,
 		// If in echo mode, we do the output conversion and need to update
 		// the needed bytes count.
 		char echoBuffer[3];
-		size_t echoBytes;
+		size_t echoBytes = 0;
 		if (echo) {
 			process_output_char(source, c, echoBuffer, &echoBytes, true);
 			if (echoBytes > bytesNeeded)