diff --git a/src/xspice/icm/digital/d_genlut/cfunc.mod b/src/xspice/icm/digital/d_genlut/cfunc.mod
index 1dd60f3d9..fe08321be 100644
--- a/src/xspice/icm/digital/d_genlut/cfunc.mod
+++ b/src/xspice/icm/digital/d_genlut/cfunc.mod
@@ -38,6 +38,7 @@ NON-STANDARD FEATURES
 
 /*=== INCLUDE FILES ====================*/
 
+#include <stdlib.h>
 #include <stdio.h>
 #include <ctype.h>
 #include <math.h>
diff --git a/src/xspice/icm/digital/d_lut/cfunc.mod b/src/xspice/icm/digital/d_lut/cfunc.mod
index 459ff2725..515e6cde4 100644
--- a/src/xspice/icm/digital/d_lut/cfunc.mod
+++ b/src/xspice/icm/digital/d_lut/cfunc.mod
@@ -38,6 +38,7 @@ NON-STANDARD FEATURES
 
 /*=== INCLUDE FILES ====================*/
 
+#include <stdlib.h>
 #include <stdio.h>
 #include <ctype.h>
 #include <math.h>