diff --git a/evildoer/gcd.c b/evildoer/gcd.c
new file mode 100644
index 0000000..9f81af5
--- /dev/null
+++ b/evildoer/gcd.c
@@ -0,0 +1,12 @@
+#include <inttypes.h>
+
+int64_t gcd(int64_t a, int64_t b) {
+    int remainder = a % b;
+
+    if (remainder == 0) {
+        return b;
+    }
+
+    return gcd(b, remainder);
+}
+