diff --git a/src/include/ngspice/ngspice.h b/src/include/ngspice/ngspice.h
index e4f1b3167..3e9465614 100644
--- a/src/include/ngspice/ngspice.h
+++ b/src/include/ngspice/ngspice.h
@@ -283,9 +283,11 @@ extern int tcl_fprintf(FILE *f, const char *format, ...);
 #elif defined SHARED_MODULE
 
 #include <errno.h>
+#include <stdarg.h>
 
 extern int sh_printf(const char *format, ...);
 extern int sh_fprintf(FILE *fd, const char *format, ...);
+extern int sh_vfprintf(FILE *fd, const char *format, va_list args);
 extern int sh_fputs(const char *input, FILE *fd);
 extern int sh_fputc(int input, FILE *fd);
 extern int sh_putc(int input, FILE *fd);
@@ -293,6 +295,9 @@ extern void SetAnalyse(char *analyse, int percent);
 
 #define HAS_PROGREP
 
+#undef vfprintf
+#define vfprintf sh_vfprintf
+
 #undef printf
 #define printf sh_printf
 
diff --git a/src/sharedspice.c b/src/sharedspice.c
index c8dbae071..2f4acd42b 100644
--- a/src/sharedspice.c
+++ b/src/sharedspice.c
@@ -898,6 +898,12 @@ add_bkpt(void)
 }
 
 
+/* use the original vprintf() in the rest of this file
+ *   instead of the redirected variant
+ */
+#undef vfprintf
+
+
 /*------------------------------------------------------*/
 /* Redefine the vfprintf() functions for callback       */
 /*------------------------------------------------------*/