diff --git a/moo/lib/err.c b/moo/lib/err.c
index fc38cc3..95363f5 100644
--- a/moo/lib/err.c
+++ b/moo/lib/err.c
@@ -331,8 +331,17 @@ const moo_ooch_t* moo_backuperrmsg (moo_t* moo)
 	return moo->errmsg.tmpbuf.ooch;
 }
 
+void moo_seterrnum (moo_t* moo, moo_errnum_t errnum)
+{
+	if (moo->shuterr) return;
+	moo->errnum = errnum; 
+	moo->errmsg.len = 0; 
+}
+
 void moo_seterrwithsyserr (moo_t* moo, int syserr)
 {
+	if (moo->shuterr) return;
+
 	if (moo->vmprim.syserrstrb)
 	{
 		moo->vmprim.syserrstrb (moo, syserr, moo->errmsg.tmpbuf.bch, MOO_COUNTOF(moo->errmsg.tmpbuf.bch));
@@ -346,13 +355,14 @@ void moo_seterrwithsyserr (moo_t* moo, int syserr)
 	}
 }
 
-
 #if defined(MOO_INCLUDE_COMPILER)
 
 void moo_setsynerrbfmt (moo_t* moo, moo_synerrnum_t num, const moo_ioloc_t* loc, const moo_oocs_t* tgt, const moo_bch_t* msgfmt, ...)
 {
 	static moo_bch_t syntax_error[] = "syntax error - ";
 
+	if (moo->shuterr) return;
+
 	if (msgfmt) 
 	{
 		va_list ap;
@@ -402,6 +412,8 @@ void moo_setsynerrufmt (moo_t* moo, moo_synerrnum_t num, const moo_ioloc_t* loc,
 {
 	static moo_bch_t syntax_error[] = "syntax error - ";
 
+	if (moo->shuterr) return;
+
 	if (msgfmt) 
 	{
 		va_list ap;
diff --git a/moo/lib/logfmt.c b/moo/lib/logfmt.c
index 51aa087..f74fccf 100644
--- a/moo/lib/logfmt.c
+++ b/moo/lib/logfmt.c
@@ -202,7 +202,7 @@ static int put_ooch (moo_t* moo, moo_oow_t mask, moo_ooch_t ch, moo_oow_t len)
 			/* no line ending - append a line terminator */
 			moo->log.ptr[moo->log.len++] = '\n';
 		}
-		moo->vmprim.log_write (moo, moo->log.last_mask, moo->log.ptr, moo->log.len);
+		vmprim_log_write (moo, moo->log.last_mask, moo->log.ptr, moo->log.len);
 		moo->log.len = 0;
 	}
 
@@ -246,7 +246,7 @@ redo:
 					/* no line ending - append a line terminator */
 					moo->log.ptr[moo->log.len++] = '\n';
 				}
-				moo->vmprim.log_write (moo, moo->log.last_mask, moo->log.ptr, moo->log.len);
+				vmprim_log_write (moo, moo->log.last_mask, moo->log.ptr, moo->log.len);
 				moo->log.len = 0;
 			}
 
@@ -297,7 +297,7 @@ static int put_oocs (moo_t* moo, moo_oow_t mask, const moo_ooch_t* ptr, moo_oow_
 			moo->log.ptr[moo->log.len++] = '\n';
 		}
 
-		moo->vmprim.log_write (moo, moo->log.last_mask, moo->log.ptr, moo->log.len);
+		vmprim_log_write (moo, moo->log.last_mask, moo->log.ptr, moo->log.len);
 		moo->log.len = 0;
 	}
 
@@ -341,7 +341,7 @@ redo:
 					/* no line ending - append a line terminator */
 					moo->log.ptr[moo->log.len++] = '\n';
 				}
-				moo->vmprim.log_write (moo, moo->log.last_mask, moo->log.ptr, moo->log.len);
+				vmprim_log_write (moo, moo->log.last_mask, moo->log.ptr, moo->log.len);
 				moo->log.len = 0;
 			}
 
@@ -639,7 +639,7 @@ moo_ooi_t moo_logbfmt (moo_t* moo, moo_oow_t mask, const moo_bch_t* fmt, ...)
 
 	if (moo->log.len > 0 && moo->log.ptr[moo->log.len - 1] == '\n')
 	{
-		moo->vmprim.log_write (moo, moo->log.last_mask, moo->log.ptr, moo->log.len);
+		vmprim_log_write (moo, moo->log.last_mask, moo->log.ptr, moo->log.len);
 		moo->log.len = 0;
 	}
 	return (x <= -1)? -1: fo.count;
@@ -667,7 +667,7 @@ moo_ooi_t moo_logufmt (moo_t* moo, moo_oow_t mask, const moo_uch_t* fmt, ...)
 
 	if (moo->log.len > 0 && moo->log.ptr[moo->log.len - 1] == '\n')
 	{
-		moo->vmprim.log_write (moo, moo->log.last_mask, moo->log.ptr, moo->log.len);
+		vmprim_log_write (moo, moo->log.last_mask, moo->log.ptr, moo->log.len);
 		moo->log.len = 0;
 	}
 
@@ -748,6 +748,8 @@ void moo_seterrbfmt (moo_t* moo, moo_errnum_t errnum, const moo_bch_t* fmt, ...)
 	va_list ap;
 	moo_fmtout_t fo;
 
+	if (moo->shuterr) return;
+
 	moo->errnum = errnum;
 	moo->errmsg.len = 0;
 
@@ -765,6 +767,8 @@ void moo_seterrufmt (moo_t* moo, moo_errnum_t errnum, const moo_uch_t* fmt, ...)
 	va_list ap;
 	moo_fmtout_t fo;
 
+	if (moo->shuterr) return;
+
 	moo->errnum = errnum;
 	moo->errmsg.len = 0;
 
@@ -782,6 +786,8 @@ void moo_seterrbfmtv (moo_t* moo, moo_errnum_t errnum, const moo_bch_t* fmt, va_
 {
 	moo_fmtout_t fo;
 
+	if (moo->shuterr) return;
+
 	moo->errnum = errnum;
 	moo->errmsg.len = 0;
 
@@ -796,6 +802,8 @@ void moo_seterrufmtv (moo_t* moo, moo_errnum_t errnum, const moo_uch_t* fmt, va_
 {
 	moo_fmtout_t fo;
 
+	if (moo->shuterr) return;
+
 	moo->errnum = errnum;
 	moo->errmsg.len = 0;
 
diff --git a/moo/lib/moo-prv.h b/moo/lib/moo-prv.h
index 41d615d..742237d 100644
--- a/moo/lib/moo-prv.h
+++ b/moo/lib/moo-prv.h
@@ -978,6 +978,16 @@ enum moo_bcode_t
 	BCODE_NOOP                       = 0xFF
 };
 
+
+/* i don't want an error raised inside the callback to override 
+ * the existing error number and message. */
+#define vmprim_log_write(moo,mask,ptr,len) do { \
+		int shuterr = (moo)->shuterr; \
+		(moo)->shuterr = 1; \
+		(moo)->vmprim.log_write (moo, mask, ptr, len); \
+		(moo)->shuterr = shuterr; \
+	} while(0)
+
 #if defined(__cplusplus)
 extern "C" {
 #endif
diff --git a/moo/lib/moo.c b/moo/lib/moo.c
index 440647b..5f4c84f 100644
--- a/moo/lib/moo.c
+++ b/moo/lib/moo.c
@@ -175,7 +175,7 @@ void moo_fini (moo_t* moo)
 	{
 		/* flush pending log messages just in case. */
 		MOO_ASSERT (moo, moo->log.ptr != MOO_NULL);
-		moo->vmprim.log_write (moo, moo->log.last_mask, moo->log.ptr, moo->log.len);
+		vmprim_log_write (moo, moo->log.last_mask, moo->log.ptr, moo->log.len);
 	}
 
 	for (cb = moo->cblist; cb; cb = cb->next)
@@ -191,7 +191,7 @@ void moo_fini (moo_t* moo)
 		 * this point because one of the callbacks could arrange to stop
 		 * logging */
 		MOO_ASSERT (moo, moo->log.ptr != MOO_NULL);
-		moo->vmprim.log_write (moo, moo->log.last_mask, moo->log.ptr, moo->log.len);
+		vmprim_log_write (moo, moo->log.last_mask, moo->log.ptr, moo->log.len);
 	}
 
 	/* deregister all callbacks */
diff --git a/moo/lib/moo.h b/moo/lib/moo.h
index 9997d85..9119f75 100644
--- a/moo/lib/moo.h
+++ b/moo/lib/moo.h
@@ -1161,7 +1161,6 @@ struct moo_t
 	moo_mmgr_t*  mmgr;
 	moo_cmgr_t*  cmgr;
 	moo_errnum_t errnum;
-
 	struct
 	{
 		union
@@ -1173,6 +1172,7 @@ struct moo_t
 		moo_ooch_t buf[2048];
 		moo_oow_t len;
 	} errmsg;
+	int shuterr;
 
 	struct
 	{
@@ -1652,7 +1652,6 @@ MOO_EXPORT void moo_fini (
 	static MOO_INLINE void moo_setcmgr (moo_t* moo, moo_cmgr_t* cmgr) { moo->cmgr = cmgr; }
 
 	static MOO_INLINE moo_errnum_t moo_geterrnum (moo_t* moo) { return moo->errnum; }
-	static MOO_INLINE void moo_seterrnum (moo_t* moo, moo_errnum_t errnum) { moo->errnum = errnum; moo->errmsg.len = 0; }
 #else
 #	define moo_getmmgr(moo) ((moo)->mmgr)
 #	define moo_getxtn(moo) ((void*)((moo) + 1))
@@ -1661,9 +1660,17 @@ MOO_EXPORT void moo_fini (
 #	define moo_setcmgr(moo,mgr) ((moo)->cmgr = (mgr))
 
 #	define moo_geterrnum(moo) ((moo)->errnum)
-#	define moo_seterrnum(moo,num) ((moo)->errmsg.len = 0, (moo)->errnum = (num))
 #endif
 
+MOO_EXPORT void moo_seterrnum (
+	moo_t*       moo, 
+	moo_errnum_t errnum
+);
+
+MOO_EXPORT void moo_seterrwithsyserr (
+	moo_t* moo,
+	int    syserr
+);
 
 MOO_EXPORT void moo_seterrbfmt (
 	moo_t*           moo,
@@ -1679,11 +1686,6 @@ MOO_EXPORT void moo_seterrufmt (
 	...
 );
 
-MOO_EXPORT void moo_seterrwithsyserr (
-	moo_t* moo,
-	int    syserr
-);
-
 MOO_EXPORT const moo_ooch_t* moo_geterrstr (
 	moo_t* moo
 );