diff --git a/src/include/ngspice/compatmode.h b/src/include/ngspice/compatmode.h
index 724ddcb69..03199cfdc 100644
--- a/src/include/ngspice/compatmode.h
+++ b/src/include/ngspice/compatmode.h
@@ -11,6 +11,6 @@ typedef enum {
   COMPATMODE_PS = 4
 } COMPATMODE_T ;
 
-extern COMPATMODE_T ngspice_compat_mode(void) ;
+extern COMPATMODE_T inp_compat_mode;
 
 #endif