diff --git a/t/10keyname.c b/t/10keyname.c
index feedbc4..0872bbc 100644
--- a/t/10keyname.c
+++ b/t/10keyname.c
@@ -5,7 +5,7 @@ int main(int argc, char *argv[])
 {
   TermKey   *tk;
   TermKeySym sym;
-  char *end;
+  const char *end;
 
   plan_tests(10);
 
diff --git a/t/12strpkey.c b/t/12strpkey.c
index cb3d3c0..28c32f5 100644
--- a/t/12strpkey.c
+++ b/t/12strpkey.c
@@ -5,7 +5,7 @@ int main(int argc, char *argv[])
 {
   TermKey      *tk;
   TermKeyKey    key;
-  char         *endp;
+  const char   *endp;
 
 #define CLEAR_KEY do { key.type = -1; key.code.codepoint = -1; key.modifiers = -1; key.utf8[0] = 0; } while(0)
 
diff --git a/t/20canon.c b/t/20canon.c
index 8d7b6ad..0460153 100644
--- a/t/20canon.c
+++ b/t/20canon.c
@@ -5,7 +5,7 @@ int main(int argc, char *argv[])
 {
   TermKey      *tk;
   TermKeyKey    key;
-  char         *endp;
+  const char   *endp;
 
 #define CLEAR_KEY do { key.type = -1; key.code.codepoint = -1; key.modifiers = -1; key.utf8[0] = 0; } while(0)
 
diff --git a/termkey.c b/termkey.c
index 1ed92fc..5813b9e 100644
--- a/termkey.c
+++ b/termkey.c
@@ -1113,7 +1113,7 @@ const char *termkey_get_keyname(TermKey *tk, TermKeySym sym)
   return "UNKNOWN";
 }
 
-char *termkey_lookup_keyname(TermKey *tk, const char *str, TermKeySym *sym)
+const char *termkey_lookup_keyname(TermKey *tk, const char *str, TermKeySym *sym)
 {
   /* We store an array, so we can't do better than a linear search. Doesn't
    * matter because user won't be calling this too often */
@@ -1133,7 +1133,7 @@ char *termkey_lookup_keyname(TermKey *tk, const char *str, TermKeySym *sym)
 TermKeySym termkey_keyname2sym(TermKey *tk, const char *keyname)
 {
   TermKeySym sym;
-  char *endp = termkey_lookup_keyname(tk, keyname, &sym);
+  const char *endp = termkey_lookup_keyname(tk, keyname, &sym);
   if(!endp || endp[0])
     return TERMKEY_SYM_UNKNOWN;
   return sym;
@@ -1255,7 +1255,7 @@ size_t termkey_strfkey(TermKey *tk, char *buffer, size_t len, TermKeyKey *key, T
       int line, col;
       termkey_interpret_mouse(tk, key, &ev, &button, &line, &col);
 
-      static char *evnames[] = { "Unknown", "Press", "Drag", "Release" };
+      static const char *evnames[] = { "Unknown", "Press", "Drag", "Release" };
 
       l = snprintf(buffer + pos, len - pos, "Mouse%s(%d)",
           evnames[ev], button);
@@ -1297,7 +1297,7 @@ size_t termkey_strfkey(TermKey *tk, char *buffer, size_t len, TermKeyKey *key, T
   return pos;
 }
 
-char *termkey_strpkey(TermKey *tk, const char *str, TermKeyKey *key, TermKeyFormat format)
+const char *termkey_strpkey(TermKey *tk, const char *str, TermKeyKey *key, TermKeyFormat format)
 {
   struct modnames *mods = &modnames[!!(format & TERMKEY_FORMAT_LONGMOD) +
                                     !!(format & TERMKEY_FORMAT_ALTISMETA) * 2];
@@ -1340,7 +1340,7 @@ char *termkey_strpkey(TermKey *tk, const char *str, TermKeyKey *key, TermKeyForm
 
   size_t nbytes;
   ssize_t snbytes;
-  char *endstr;
+  const char *endstr;
 
   if((endstr = termkey_lookup_keyname(tk, str, &key->code.sym))) {
     key->type = TERMKEY_TYPE_KEYSYM;
@@ -1351,7 +1351,7 @@ char *termkey_strpkey(TermKey *tk, const char *str, TermKeyKey *key, TermKeyForm
     str += snbytes;
   }
   // Unicode must be last
-  else if(parse_utf8((unsigned char *)str, strlen(str), &key->code.codepoint, &nbytes) == TERMKEY_RES_KEY) {
+  else if(parse_utf8((unsigned const char *)str, strlen(str), &key->code.codepoint, &nbytes) == TERMKEY_RES_KEY) {
     key->type = TERMKEY_TYPE_UNICODE;
     fill_utf8(key);
     str += nbytes;
diff --git a/termkey.h.in b/termkey.h.in
index 95f315b..677d5e7 100644
--- a/termkey.h.in
+++ b/termkey.h.in
@@ -198,7 +198,7 @@ size_t termkey_push_bytes(TermKey *tk, const char *bytes, size_t len);
 
 TermKeySym termkey_register_keyname(TermKey *tk, TermKeySym sym, const char *name);
 const char *termkey_get_keyname(TermKey *tk, TermKeySym sym);
-char       *termkey_lookup_keyname(TermKey *tk, const char *str, TermKeySym *sym);
+const char *termkey_lookup_keyname(TermKey *tk, const char *str, TermKeySym *sym);
 
 TermKeySym termkey_keyname2sym(TermKey *tk, const char *keyname); 
 
@@ -223,8 +223,8 @@ typedef enum {
 
 #define TERMKEY_FORMAT_VIM (TERMKEY_FORMAT_ALTISMETA|TERMKEY_FORMAT_WRAPBRACKET)
 
-size_t  termkey_strfkey(TermKey *tk, char *buffer, size_t len, TermKeyKey *key, TermKeyFormat format);
-char   *termkey_strpkey(TermKey *tk, const char *str, TermKeyKey *key, TermKeyFormat format);
+size_t      termkey_strfkey(TermKey *tk, char *buffer, size_t len, TermKeyKey *key, TermKeyFormat format);
+const char *termkey_strpkey(TermKey *tk, const char *str, TermKeyKey *key, TermKeyFormat format);
 
 int termkey_keycmp(TermKey *tk, const TermKeyKey *key1, const TermKeyKey *key2);