diff --git a/src/macro_collections.h b/src/macro_collections.h
index 40a408c..593291a 100644
--- a/src/macro_collections.h
+++ b/src/macro_collections.h
@@ -11,21 +11,19 @@
 #ifndef CMC_MACRO_COLLECTIONS_H
 #define CMC_MACRO_COLLECTIONS_H
 
-#define CMC_CONCATH_(C) CMC_WRAPGEN_##C##_HEADER
-#define CMC_CONCATC_(C) CMC_WRAPGEN_##C##_SOURCE
+#define CMC_CONCAT_(C, T) CMC_WRAPGEN_##C##_##T
 
-#define CMC_CONCATH(C) CMC_CONCATH_(C)
-#define CMC_CONCATC(C) CMC_CONCATC_(C)
+#define CMC_CONCAT(C, T) CMC_CONCAT_(C, T)
 
 #define CMC_COLLECTION_GENERATE(C, PFX, SNAME, K, V)    \
     CMC_COLLECTION_GENERATE_HEADER(C, PFX, SNAME, K, V) \
     CMC_COLLECTION_GENERATE_SOURCE(C, PFX, SNAME, K, V)
 
 #define CMC_COLLECTION_GENERATE_HEADER(C, PFX, SNAME, K, V) \
-    CMC_CONCATH(C)(PFX, SNAME, K, V)
+    CMC_CONCAT(C, HEADER)(PFX, SNAME, K, V)
 
 #define CMC_COLLECTION_GENERATE_SOURCE(C, PFX, SNAME, K, V) \
-    CMC_CONCATC(C)(PFX, SNAME, K, V)
+    CMC_CONCAT(C, SOURCE)(PFX, SNAME, K, V)
 
 #include "cmc/bidimap.h"      /* Added in 26/09/2019 */
 #include "cmc/deque.h"        /* Added in 20/03/2019 */