diff --git a/src/vim9execute.c b/src/vim9execute.c
index 8e27166..921e2ca 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -4448,6 +4448,7 @@
 		    CLEAR_FIELD(ea);
 		    ea.cmd = ea.arg = iptr->isn_arg.string;
 		    ga_init2(&lines_to_free, sizeof(char_u *), 50);
+		    SOURCING_LNUM = iptr->isn_lnum;
 		    define_function(&ea, NULL, &lines_to_free, 0);
 		    ga_clear_strings(&lines_to_free);
 		}