diff --git a/src/database.c b/src/database.c
index 9107395..662c218 100644
--- a/src/database.c
+++ b/src/database.c
@@ -234,7 +234,7 @@ simdb_records_count(simdb_t * const db) {
   return size / SIMDB_REC_LEN;
 }
 
-float
+static float
 ratio_from_rec_data(unsigned char * const data) {
   uint16_t iw, ih;
 
diff --git a/src/database.h b/src/database.h
index 30639c2..58f4b8f 100644
--- a/src/database.h
+++ b/src/database.h
@@ -135,9 +135,6 @@ void simdb_close(simdb_t *db);
  */
 const char * simdb_error(int code);
 
-float
-ratio_from_rec_data(unsigned char * const data);
-
 /**
  * @returns: >0 if found some matches, 0 if nothing found, <0 on error
  */