diff --git a/numeric_base.cpp b/numeric_base.cpp
index 389fa72..4850588 100644
--- a/numeric_base.cpp
+++ b/numeric_base.cpp
@@ -1,6 +1,7 @@
 #include "includes/numeric_base.hpp"
 #include <string>
 #include <cmath>
+#include <cctype>
 #include <algorithm>
 
 std::string possible_chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
@@ -15,7 +16,7 @@ unsigned int to_decimal(std::string num, int from_base) {
 	compute the value using  */
 	for (int i=0; i < (int)num.length(); i++) {
 		current_char = num.at(i);
-		index = possible_chars.find(current_char);
+		index = possible_chars.find(toupper(current_char)); // Convert the character to upper-case, so that the earliest match is detected
 		value += pow(from_base, num.length() - i - 1) * index;
 	}