diff --git a/src/if_perl.xs b/src/if_perl.xs
index a5b3f28..180fce6 100644
--- a/src/if_perl.xs
+++ b/src/if_perl.xs
@@ -338,7 +338,7 @@
  */
 static HANDLE hPerlLib = NULL;
 
-static PerlInterpreter* (*perl_alloc)();
+static PerlInterpreter* (*perl_alloc)(void);
 static void (*perl_construct)(PerlInterpreter*);
 static void (*perl_destruct)(PerlInterpreter*);
 static void (*perl_free)(PerlInterpreter*);