diff --git a/src/evalvars.c b/src/evalvars.c
index a946c75..ecd0ce6 100644
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -524,7 +524,7 @@
     static void
 list_script_vars(int *first)
 {
-    if (current_sctx.sc_sid > 0 && current_sctx.sc_sid <= script_items.ga_len)
+    if (SCRIPT_ID_VALID(current_sctx.sc_sid))
 	list_hashtable_vars(&SCRIPT_VARS(current_sctx.sc_sid),
 							   "s:", FALSE, first);
 }
@@ -2609,7 +2609,7 @@
 {
     scid_T sid = current_sctx.sc_sid;
 
-    if (sid > 0 && sid <= script_items.ga_len)
+    if (SCRIPT_ID_VALID(sid))
 	return &SCRIPT_VARS(sid);
     return NULL;
 }
diff --git a/src/globals.h b/src/globals.h
index e883c56..1a764b5 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -297,8 +297,9 @@
 # endif
 EXTERN garray_T script_items INIT5(0, 0, sizeof(scriptitem_T *), 20, NULL);
 # define SCRIPT_ITEM(id)    (((scriptitem_T **)script_items.ga_data)[(id) - 1])
-# define SCRIPT_SV(id)	    (SCRIPT_ITEM(id)->sn_vars)
-# define SCRIPT_VARS(id)    (SCRIPT_SV(id)->sv_dict.dv_hashtab)
+# define SCRIPT_ID_VALID(id)    ((id) > 0 && (id) <= script_items.ga_len)
+# define SCRIPT_SV(id)		(SCRIPT_ITEM(id)->sn_vars)
+# define SCRIPT_VARS(id)	(SCRIPT_SV(id)->sv_dict.dv_hashtab)
 
 # define FUNCLINE(fp, j)	((char_u **)(fp->uf_lines.ga_data))[j]
 
diff --git a/src/profiler.c b/src/profiler.c
index 647934d..7896897 100644
--- a/src/profiler.c
+++ b/src/profiler.c
@@ -761,7 +761,7 @@
 {
     scriptitem_T    *si;
 
-    if (current_sctx.sc_sid > 0 && current_sctx.sc_sid <= script_items.ga_len)
+    if (SCRIPT_ID_VALID(current_sctx.sc_sid))
     {
 	si = SCRIPT_ITEM(current_sctx.sc_sid);
 	if (si->sn_prof_on && si->sn_pr_nest++ == 0)
@@ -778,7 +778,7 @@
 {
     scriptitem_T    *si;
 
-    if (current_sctx.sc_sid > 0 && current_sctx.sc_sid <= script_items.ga_len)
+    if (SCRIPT_ID_VALID(current_sctx.sc_sid))
     {
 	si = SCRIPT_ITEM(current_sctx.sc_sid);
 	if (si->sn_prof_on && --si->sn_pr_nest == 0)
@@ -903,7 +903,7 @@
     scriptitem_T    *si;
     sn_prl_T	    *pp;
 
-    if (current_sctx.sc_sid <= 0 || current_sctx.sc_sid > script_items.ga_len)
+    if (!SCRIPT_ID_VALID(current_sctx.sc_sid))
 	return;
     si = SCRIPT_ITEM(current_sctx.sc_sid);
     if (si->sn_prof_on && SOURCING_LNUM >= 1)
@@ -938,7 +938,7 @@
 {
     scriptitem_T    *si;
 
-    if (current_sctx.sc_sid <= 0 || current_sctx.sc_sid > script_items.ga_len)
+    if (!SCRIPT_ID_VALID(current_sctx.sc_sid))
 	return;
     si = SCRIPT_ITEM(current_sctx.sc_sid);
     if (si->sn_prof_on && si->sn_prl_idx >= 0)
@@ -954,7 +954,7 @@
     scriptitem_T    *si;
     sn_prl_T	    *pp;
 
-    if (current_sctx.sc_sid <= 0 || current_sctx.sc_sid > script_items.ga_len)
+    if (!SCRIPT_ID_VALID(current_sctx.sc_sid))
 	return;
     si = SCRIPT_ITEM(current_sctx.sc_sid);
     if (si->sn_prof_on && si->sn_prl_idx >= 0
diff --git a/src/scriptfile.c b/src/scriptfile.c
index 27d0eb2..e075236 100644
--- a/src/scriptfile.c
+++ b/src/scriptfile.c
@@ -1517,7 +1517,7 @@
     if (eap->addr_count > 0)
     {
 	// :script {scriptId}: edit the script
-	if (eap->line2 < 1 || eap->line2 > script_items.ga_len)
+	if (!SCRIPT_ID_VALID(eap->line2))
 	    emsg(_(e_invarg));
 	else
 	{
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index 054fe4c..49aacb0 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -4,6 +4,7 @@
 source term_util.vim
 source view_util.vim
 source vim9.vim
+source shared.vim
 
 def Test_syntax()
   let var = 234
@@ -3252,6 +3253,14 @@
   delete('rtp', 'rf')
 enddef
 
+def Test_invalid_sid()
+  assert_fails('func <SNR>1234_func', 'E123:')
+  if RunVim([], ['wq Xdidit'], '+"func <SNR>1_func"')
+    call assert_equal([], readfile('Xdidit'))
+  endif
+  delete('Xdidit')
+enddef
+
 " Keep this last, it messes up highlighting.
 def Test_substitute_cmd()
   new
diff --git a/src/version.c b/src/version.c
index 9e3430a..ba308cd 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1539,
+/**/
     1538,
 /**/
     1537,
diff --git a/src/vim9compile.c b/src/vim9compile.c
index 5e4bfdb..bec6988 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -1661,7 +1661,7 @@
     int		    idx;
 
     // First look the name up in the hashtable.
-    if (sid <= 0 || sid > script_items.ga_len)
+    if (!SCRIPT_ID_VALID(sid))
 	return -1;
     ht = &SCRIPT_VARS(sid);
     di = find_var_in_ht(ht, 0, name, TRUE);
@@ -1692,7 +1692,7 @@
 {
     int		    idx;
 
-    if (current_sctx.sc_sid <= 0)
+    if (!SCRIPT_ID_VALID(current_sctx.sc_sid))
 	return NULL;
     if (cctx != NULL)
 	for (idx = 0; idx < cctx->ctx_imports.ga_len; ++idx)
@@ -1712,9 +1712,12 @@
     imported_T *
 find_imported_in_script(char_u *name, size_t len, int sid)
 {
-    scriptitem_T    *si = SCRIPT_ITEM(sid);
+    scriptitem_T    *si;
     int		    idx;
 
+    if (!SCRIPT_ID_VALID(sid))
+	return NULL;
+    si = SCRIPT_ITEM(sid);
     for (idx = 0; idx < si->sn_imports.ga_len; ++idx)
     {
 	imported_T *import = ((imported_T *)si->sn_imports.ga_data) + idx;
@@ -1966,10 +1969,14 @@
 	char_u **end,	    // end of variable
 	int    error)	    // when TRUE may give error
 {
-    scriptitem_T    *si = SCRIPT_ITEM(current_sctx.sc_sid);
-    int		    idx = get_script_item_idx(current_sctx.sc_sid, name, FALSE);
+    scriptitem_T    *si;
+    int		    idx;
     imported_T	    *import;
 
+    if (!SCRIPT_ID_VALID(current_sctx.sc_sid))
+	return FAIL;
+    si = SCRIPT_ITEM(current_sctx.sc_sid);
+    idx = get_script_item_idx(current_sctx.sc_sid, name, FALSE);
     if (idx == -1 || si->sn_version != SCRIPT_VERSION_VIM9)
     {
 	// variable is not in sn_var_vals: old style script.
@@ -4750,15 +4757,18 @@
 			scriptvar_sid = current_sctx.sc_sid;
 			if (import != NULL)
 			    scriptvar_sid = import->imp_sid;
-			scriptvar_idx = get_script_item_idx(scriptvar_sid,
-								rawname, TRUE);
-			if (scriptvar_idx >= 0)
+			if (SCRIPT_ID_VALID(scriptvar_sid))
 			{
-			    scriptitem_T *si = SCRIPT_ITEM(scriptvar_sid);
-			    svar_T	     *sv =
+			    scriptvar_idx = get_script_item_idx(scriptvar_sid,
+								rawname, TRUE);
+			    if (scriptvar_idx > 0)
+			    {
+				scriptitem_T *si = SCRIPT_ITEM(scriptvar_sid);
+				svar_T	     *sv =
 					    ((svar_T *)si->sn_var_vals.ga_data)
 							       + scriptvar_idx;
-			    type = sv->sv_type;
+				type = sv->sv_type;
+			    }
 			}
 		    }
 		    else if (name[1] == ':' && name[2] != NUL)