diff --git a/src/vim9compile.c b/src/vim9compile.c
index c5d92aa..2c52280 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -3362,6 +3362,8 @@
     while (p > start)
     {
 	--p;
+	while (VIM_ISWHITE(*p))
+	    --p;
 	if (*p == '-' || *p == '+')
 	{
 	    int	    negate = *p == '-';