diff --git a/src/include/ngspice/cktdefs.h b/src/include/ngspice/cktdefs.h
index 32c7359d0..f4b2aba47 100644
--- a/src/include/ngspice/cktdefs.h
+++ b/src/include/ngspice/cktdefs.h
@@ -3,8 +3,8 @@
  * Modified 1999 Paolo Nenzi - Removed non STDC definitions
  * Modified 2000 AlansFixes
  */
-#ifndef CKT_H
-#define CKT_H
+#ifndef ngspice_CKTDEFS_H
+#define ngspice_CKTDEFS_H
 
 #include "ngspice/typedefs.h"
 
diff --git a/src/spicelib/devices/ndev/ndevexch.h b/src/spicelib/devices/ndev/ndevexch.h
index ca9d2b12b..9fde3312c 100644
--- a/src/spicelib/devices/ndev/ndevexch.h
+++ b/src/spicelib/devices/ndev/ndevexch.h
@@ -14,7 +14,7 @@
 #define NDEV_AC_LOAD            0x0010
 #define NDEV_PZ_LOAD            0x0020
 
-#ifndef CKT_H
+#ifndef ngspice_CKTDEFS_H
 /* defines for CKTmode */
 /* this should be the same as cktdefs.h */
 /* old 'mode' parameters */