diff --git a/stk500v2/main.cpp b/stk500v2/main.cpp
index a5fa85a..c8f0b35 100644
--- a/stk500v2/main.cpp
+++ b/stk500v2/main.cpp
@@ -340,15 +340,15 @@ static inline void performChipErase()
 	};
 
 	constexpr auto getBootloaderSize = []() -> uint16_t {
-		const auto extendedFuse = boot_lock_fuse_bits_get(GET_HIGH_FUSE_BITS);
+		const auto highFuse = boot_lock_fuse_bits_get(GET_HIGH_FUSE_BITS);
 		constexpr auto BOOTSZ0 = 1;
 		constexpr auto BOOTSZ1 = 2;
 
-		if (extendedFuse & (1 << BOOTSZ1 | 1 << BOOTSZ0))
+		if (highFuse & (1 << BOOTSZ1) && highFuse & (1 << BOOTSZ0))
 			return 256 * 2;
-		else if (extendedFuse & (1 << BOOTSZ1))
+		else if (highFuse & (1 << BOOTSZ1))
 			return 512 * 2;
-		else if (extendedFuse & (1 << BOOTSZ0))
+		else if (highFuse & (1 << BOOTSZ0))
 			return 1024 * 2;
 		return 2048 * 2;
 	};