diff --git a/descrip.mms b/descrip.mms
index a0283606..f2d38775 100644
--- a/descrip.mms
+++ b/descrip.mms
@@ -316,7 +316,7 @@ ATT3B2_SOURCE = $(ATT3B2_DIR)3B2_CPU.C,$(ATT3B2_DIR)3B2_DMAC.C,\
                 $(ATT3B2_DIR)3B2_IO.C,$(ATT3B2_DIR)3B2_IU.C,\
                 $(ATT3B2_DIR)3B2_MMU.C,$(ATT3B2_DIR)3B2_SYS.C,\
                 $(ATT3B2_DIR)3B2_SYSDEV.C
-ALTAIR_OPTIONS = /INCL=($(SIMH_DIR),$(ATT3B2_DIR))/DEF=($(CC_DEFS))
+ATT3B2_OPTIONS = /INCL=($(SIMH_DIR),$(ATT3B2_DIR))/DEF=($(CC_DEFS))
 
 # MITS Altair Simulator Definitions.
 #
diff --git a/sim_defs.h b/sim_defs.h
index e3d09f25..b0129533 100644
--- a/sim_defs.h
+++ b/sim_defs.h
@@ -115,6 +115,10 @@
 #if defined(_MSC_VER) && (_MSC_VER < 1900)
 #define snprintf _snprintf      /* poor man's snprintf which will work most of the time but has different return value */
 #endif
+#if defined(__VAX)
+extern int sim_vax_snprintf(char *buf, size_t buf_size, const char *fmt, ...);
+#define snprintf sim_vax_snprintf
+#endif
 #include <stdarg.h>
 #include <string.h>
 #include <errno.h>
diff --git a/sim_fio.c b/sim_fio.c
index 2f77b3d8..d05e18f3 100644
--- a/sim_fio.c
+++ b/sim_fio.c
@@ -599,3 +599,20 @@ free (shmem);
 }
 
 #endif
+
+#if defined(__VAX)
+/* 
+ * We privide a 'basic' snprintf, which 'might' overrun a buffer, but
+ * the actual use cases don't on other platforms and none of the callers
+ * care about the function return value.
+ */
+int sim_vax_snprintf(char *buf, size_t buf_size, const char *fmt, ...)
+{
+va_list arglist;
+
+va_start (arglist, fmt);
+vsprintf (buf, fmt, arglist);
+va_end (arglist);
+return 0;
+}
+#endif