diff --git a/Devmapper.h b/Devmapper.h
index d6cdd05..52e2bed 100644
--- a/Devmapper.h
+++ b/Devmapper.h
@@ -22,8 +22,8 @@
 
 class Devmapper {
 public:
-    static int create(const char *name, const char *loopFile, const char *key, int sizeMb,
-                      char *buffer, size_t len);
+    static int create(const char *name, const char *loopFile, const char *key,
+                      unsigned int numSectors, char *buffer, size_t len);
     static int destroy(const char *name);
     static int lookupActive(const char *name, char *buffer, size_t len);
 private: