diff --git a/include/span.hpp b/include/span.hpp
index 397887c..24de972 100644
--- a/include/span.hpp
+++ b/include/span.hpp
@@ -19,12 +19,16 @@ namespace hv
     
     inline T& operator[](std::size_t index)
     {
+#ifdef DEBUG
       if (index>=len) throw "tried to index out of bounds of array";
+#endif
       return ptr[index];
     }
     inline const T& operator[](std::size_t index) const
     {
+#ifdef DEBUG
       if (index>=len) throw "tried to index out of bounds of array";
+#endif
       return ptr[index];
     }
 
diff --git a/src/hex.cpp b/src/hex.cpp
index e32f543..3a0521d 100644
--- a/src/hex.cpp
+++ b/src/hex.cpp
@@ -69,19 +69,21 @@ namespace hv {
 #define S
 #endif
 		fmt::print("0x{:016x}  ", offset);
+		char hxbuf[3];
+		std::size_t i=0;
 		char ascii[1 + ROW_SZ];
+
 		ascii[ROW_SZ] = 0;
-		std::size_t i=0;
-		char hxbuf[3];
 		hxbuf[2] = 0;
 		for(;i<memory.size();i++) {
 			if (i && i % ROW_SZ == 0) {
 				prints("  ", S ascii);
 				fmt::print("\n0x{:016x}  ", i+offset);
 			}
-			hex02(memory[i], hxbuf);
+			unsigned char idx = memory[i];
+			hex02(idx, hxbuf);
 			prints(hxbuf, " ");
-			ascii[i%ROW_SZ] = ascii_map[memory[i]];
+			ascii[i%ROW_SZ] = ascii_map[idx];
 		}
 		if (memory.size() % ROW_SZ != 0)
 		{