diff --git a/unset_trace.c b/unset_trace.c
index 68deb15..df10676 100644
--- a/unset_trace.c
+++ b/unset_trace.c
@@ -2,6 +2,6 @@
 
 #include "Python.h"
 
-void unset_trace() {
+void unset_trace(void) {
     PyEval_SetTrace(NULL, NULL);
 }
diff --git a/unset_trace.h b/unset_trace.h
index 03df5d8..59cf13c 100644
--- a/unset_trace.h
+++ b/unset_trace.h
@@ -1 +1 @@
-void unset_trace();
+void unset_trace(void);