diff --git a/src/soter/soter.h b/src/soter/soter.h
index 9df93ecdd..d62f79abc 100644
--- a/src/soter/soter.h
+++ b/src/soter/soter.h
@@ -53,6 +53,6 @@
  *  @return version string
  *
  */
-const char* soter_version();
+const char* soter_version(void);
 /**@}*/
 #endif /* SOTER_H */
diff --git a/src/themis/themis.h b/src/themis/themis.h
index fe9b396d4..2d47a6bef 100644
--- a/src/themis/themis.h
+++ b/src/themis/themis.h
@@ -38,7 +38,7 @@
 #include <themis/secure_session.h>
 #include <themis/secure_comparator.h>
 
-const char* themis_version();
+const char* themis_version(void);
 
 /** @} */
 #endif /* THEMIS_H */