diff --git a/ex03/main.c b/ex03/main.c
index 9e51d6a..a1ae93f 100644
--- a/ex03/main.c
+++ b/ex03/main.c
@@ -14,10 +14,10 @@ int main(int argc, char *argv[]) {
   unsigned char buf[512] = {0};
   size_t len = hex_to_bytes(buf, argv[1]);
 
-  unsigned char cur[512];
+  char cur[512];
   double min_score = INFINITY;
-  unsigned char key;
-  unsigned char best[512];
+  char key;
+  char best[512];
   // Test for keys from A to z
   for (char c = 65; c < 127; ++c) {
     for (size_t i = 0; i < len; ++i) {
diff --git a/ex04/main.c b/ex04/main.c
index e718d21..e10b596 100644
--- a/ex04/main.c
+++ b/ex04/main.c
@@ -31,7 +31,7 @@ int main(int argc, char *argv[]) {
     unsigned char buf[512] = {0};
     len = hex_to_bytes(buf, line);
 
-    unsigned char cur[512] = {'\0'};
+    char cur[512] = {'\0'};
     for (char c = 32; c < 127; ++c) {
       for (size_t i = 0; i < len; ++i) {
         cur[i] = buf[i] ^ c;
diff --git a/utils.c b/utils.c
index 20e506e..d4aef38 100644
--- a/utils.c
+++ b/utils.c
@@ -50,7 +50,7 @@ char *bytes_to_base64(char *out, const unsigned char in[static 1], size_t len) {
   return out;
 }
 
-double frequency_score(unsigned char *buf, size_t len) {
+double frequency_score(const char *buf, size_t len) {
   static const double english_freqs[27] = {
       0.08167, 0.01492, 0.02782, 0.04253, 0.12702, 0.02228, 0.02015, // A-G
       0.06094, 0.06966, 0.00153, 0.00772, 0.04025, 0.02406, 0.06749, // H-N
diff --git a/utils.h b/utils.h
index 8bff75f..4cb4d2a 100644
--- a/utils.h
+++ b/utils.h
@@ -6,7 +6,7 @@
 unsigned char hex_to_byte(const char c);
 size_t hex_to_bytes(unsigned char *out, const char hex[static 1]);
 char *bytes_to_base64(char *out, const unsigned char in[static 1], size_t len);
-double frequency_score(unsigned char *buf, size_t len);
+double frequency_score(const char *buf, size_t len);
 unsigned int hamming(const char *s1, const char *s2);
 
 #endif /* UTILS_H */