diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 04c3b46..987e92d 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -8268,8 +8268,10 @@
 #define SPEC_SFILE  (SPEC_CFILE + 1)
 		    "<slnum>",		// ":so" file line number
 #define SPEC_SLNUM  (SPEC_SFILE + 1)
+		    "<stack>",		// call stack
+#define SPEC_STACK  (SPEC_SLNUM + 1)
 		    "<afile>",		// autocommand file name
-#define SPEC_AFILE  (SPEC_SLNUM + 1)
+#define SPEC_AFILE  (SPEC_STACK + 1)
 		    "<abuf>",		// autocommand buffer number
 #define SPEC_ABUF   (SPEC_AFILE + 1)
 		    "<amatch>",		// autocommand match name
@@ -8520,10 +8522,13 @@
 		break;
 
 	case SPEC_SFILE:	// file name for ":so" command
-		result = estack_sfile();
+	case SPEC_STACK:	// call stack
+		result = estack_sfile(spec_idx == SPEC_SFILE);
 		if (result == NULL)
 		{
-		    *errormsg = _("E498: no :source file name to substitute for \"<sfile>\"");
+		    *errormsg = spec_idx == SPEC_SFILE
+			? _("E498: no :source file name to substitute for \"<sfile>\"")
+			: _("E489: no call stack to substitute for \"<stack>\"");
 		    return NULL;
 		}
 		resultbuf = result;	    // remember allocated string