diff --git a/btree_key.cpp b/btree_key.cpp
index 8b16fce..996ea48 100644
--- a/btree_key.cpp
+++ b/btree_key.cpp
@@ -14,26 +14,60 @@
 
 int 
 compareKeyPChar(void * key1, void * key2) {
-  return strcmp((char *)key1, (char *)key2);
+  const char * charKey1 = static_cast<const char *>(key1);
+  const char * charKey2 = static_cast<const char *>(key2);
+  return strcmp(charKey1, charKey2);
 } // compareKeyPChar
 
 int 
-compareKeySingle(void * , void * ) {
+compareKeySingle(void * key1, void * key2) {
+  if ((key1 == NULL) || (key2 == NULL)) return 0;
+
+  const float * floatKey1 = static_cast<const float *>(key1);
+  const float * floatKey2 = static_cast<const float *>(key2);
+
+  if (*floatKey1 < *floatKey2) return -1;
+  else if (*floatKey1 > *floatKey2) return 1;
+
   return 0;
 } // compareKeySingle
 
 int 
-compareKeyDouble(void * , void * ) {
+compareKeyDouble(void * key1, void * key2) {
+  if ((key1 == NULL) || (key2 == NULL)) return 0;
+
+  const double * doubleKey1 = static_cast<const double *>(key1);
+  const double * doubleKey2 = static_cast<const double *>(key2);
+
+  if (*doubleKey1 < *doubleKey2) return -1;
+  else if (*doubleKey1 > *doubleKey2) return 1;
+  
   return 0;
 } // compareKeyDouble
 
 int 
 compareKeyInt32(void * , void * ) {
+  if ((key1 == NULL) || (key2 == NULL)) return 0;
+
+  const int32 * int32Key1 = static_cast<const int32 *>(key1);
+  const int32 * int32Key2 = static_cast<const int32 *>(key2);
+
+  if (*int32Key1 < *int32Key2) return -1;
+  else if (*int32Key1 > *int32Key2) return 1;
+ 
   return 0;
 } // compareKeyInt32
 
 int 
-compareKeyInt64(void * , void * ) {
+compareKeyInt64(void * key1, void * key2) {
+  if ((key1 == NULL) || (key2 == NULL)) return 0;
+
+  const int64 * int64Key1 = static_cast<const int64 *>(key1);
+  const int64 * int64Key2 = static_cast<const int64 *>(key2);
+
+  if (*int64Key1 < *int64Key2) return -1;
+  else if (*int64Key1 > *int64Key2) return 1;
+
   return 0;
 } // compareKeyInt64