diff --git a/src/include/ngspice/cmproto.h b/src/include/ngspice/cmproto.h
index 75e474241..5692b5a21 100644
--- a/src/include/ngspice/cmproto.h
+++ b/src/include/ngspice/cmproto.h
@@ -85,6 +85,13 @@ int  cm_event_queue(double time);
 char *cm_message_get_errmsg(void);
 int  cm_message_send(char *msg);
 
+#ifdef __GNUC__
+int cm_message_printf(const char *fmt, ...) __attribute__ ((format (__printf__, 1, 2)));
+#else
+int cm_message_printf(const char *fmt, ...);
+#endif
+
+
 double cm_netlist_get_c(void);
 double cm_netlist_get_l(void);
 
diff --git a/src/xspice/icm/analog/file_source/cfunc.mod b/src/xspice/icm/analog/file_source/cfunc.mod
index 4493f64dd..7ec3d03c4 100644
--- a/src/xspice/icm/analog/file_source/cfunc.mod
+++ b/src/xspice/icm/analog/file_source/cfunc.mod
@@ -179,9 +179,7 @@ void cm_filesource(ARGS)   /* structure holding parms, inputs, outputs, etc.
                 free(p);
             } 
             if (!loc->state->fp) {
-                char msg[512];
-                snprintf(msg, sizeof(msg), "cannot open file %s", PARAM(file));
-                cm_message_send(msg);
+                cm_message_printf("cannot open file %s", PARAM(file));
                 loc->state->atend = 1;
             }
         }
diff --git a/src/xspice/icm/digital/d_source/cfunc.mod b/src/xspice/icm/digital/d_source/cfunc.mod
index 7540ff5d7..768b82585 100644
--- a/src/xspice/icm/digital/d_source/cfunc.mod
+++ b/src/xspice/icm/digital/d_source/cfunc.mod
@@ -936,11 +936,8 @@ void cm_d_source(ARGS)
                 source = fopen(p, "r");
                 free(p);
             }
-            if (!source) {
-                char msg[512];
-                snprintf(msg, sizeof(msg), "cannot open file %s", PARAM(input_file));
-                cm_message_send(msg);
-            }
+            if (!source)
+                cm_message_printf("cannot open file %s", PARAM(input_file));
         }
 
         /* increment counter if not a comment until EOF reached... */
diff --git a/src/xspice/icm/dlmain.c b/src/xspice/icm/dlmain.c
index 47e2d1fd2..ab228ca0b 100644
--- a/src/xspice/icm/dlmain.c
+++ b/src/xspice/icm/dlmain.c
@@ -17,6 +17,8 @@
 #include  <stdlib.h>
 #include  <string.h>
 
+#include  <stdarg.h>
+
 
 //////////////////////////////////////////////////////////////////////////////
 //////////////////////////////////////////////////////////////////////////////
@@ -452,3 +454,41 @@ FILE *fopen_with_path(const char *path, const char *mode)
     fp =  fopen(path, mode);
     return fp;
 }
+
+
+int
+cm_message_printf(const char *fmt, ...)
+{
+    char buf[1024];
+    char *p = buf;
+    int size = sizeof(buf);
+    int rv;
+
+    for (;;) {
+
+        int nchars;
+        va_list ap;
+
+        va_start(ap, fmt);
+        nchars = vsnprintf(p, (size_t) size, fmt, ap);
+        va_end(ap);
+
+        if (nchars == -1) {     // compatibility to old implementations
+            size *= 2;
+        } else if (size < nchars + 1) {
+            size = nchars + 1;
+        } else {
+            break;
+        }
+
+        if (p == buf)
+            p = tmalloc((size_t) size * sizeof(char));
+        else
+            p = trealloc(p, (size_t) size * sizeof(char));
+    }
+
+    rv = cm_message_send(p);
+    if (p != buf)
+        txfree(p);
+    return rv;
+}