diff --git a/Common/Data/Encoding/Shiftjis.h b/Common/Data/Encoding/Shiftjis.h
index 7d73ea381a..bcda427d1c 100644
--- a/Common/Data/Encoding/Shiftjis.h
+++ b/Common/Data/Encoding/Shiftjis.h
@@ -110,8 +110,9 @@ struct ShiftJIS {
 		} else if (row < 0x5F) {
 			// Reduce by 0x40 to account for the above range.
 			*dest++ = 0xE0 + ((row - 0x40 + 1) >> 1);
-		} else if (row >= 0x80) {
-			// TODO
+		} else {
+			// Rows 0x5F-0x7F and 0x80+ are not encodable.
+			return 0;
 		}
 
 		if (row & 1) {
diff --git a/Common/Data/Encoding/Utf8.cpp b/Common/Data/Encoding/Utf8.cpp
index 737b049bcd..1bc0c1ddb4 100644
--- a/Common/Data/Encoding/Utf8.cpp
+++ b/Common/Data/Encoding/Utf8.cpp
@@ -207,7 +207,7 @@ void ConvertUTF8ToWString(wchar_t *dest, size_t destSize, std::string_view sourc
 	destSize -= 1;  // account for the \0.
 	int size = (int)MultiByteToWideChar(CP_UTF8, 0, source.data(), len, NULL, 0);
 	MultiByteToWideChar(CP_UTF8, 0, source.data(), len, dest, std::min((int)destSize, size));
-	dest[size] = 0;
+	dest[std::min(size, (int)destSize)] = 0;
 }
 
 std::wstring ConvertUTF8ToWString(const std::string_view source) {