diff --git a/misc/factor.vim.fgen b/misc/factor.vim.fgen
index 272fb64114..d6b2557a04 100644
--- a/misc/factor.vim.fgen
+++ b/misc/factor.vim.fgen
@@ -162,8 +162,8 @@ syn match factorMultiStringContents /.*/ contained
 "syn match factorStackEffectErr /\<)\>/
 "syn region factorStackEffectErr start=/\<(\>/ end=/\<)\>/
 "syn region factorStackEffect start=/\<(\>/ end=/\<)\>/ contained
-syn match factorStackEffect /\<(\s\(.*\s\)\?--\(\s.*\)\?\s)\>/ contained
-syn match factorLiteralStackEffect /\<((\s\(.*\s\)\?--\(\s.*\)\?\s))\>/
+syn match factorStackEffect /\<(\s\(\S*\s\)\?--\(\s\S*\)\?\s)\>/ contained
+syn match factorLiteralStackEffect /\<((\s\(\S*\s\)\?--\(\s\S*\)\?\s))\>/
 
 "adapted from lisp.vim
 if exists("g:factor_norainbow")
diff --git a/misc/vim/syntax/factor.vim b/misc/vim/syntax/factor.vim
index 7d9e483792..793439ebcd 100644
--- a/misc/vim/syntax/factor.vim
+++ b/misc/vim/syntax/factor.vim
@@ -149,8 +149,8 @@ syn match factorMultiStringContents /.*/ contained
 "syn match factorStackEffectErr /\<)\>/
 "syn region factorStackEffectErr start=/\<(\>/ end=/\<)\>/
 "syn region factorStackEffect start=/\<(\>/ end=/\<)\>/ contained
-syn match factorStackEffect /\<(\s\(.*\s\)\?--\(\s.*\)\?\s)\>/ contained
-syn match factorLiteralStackEffect /\<((\s\(.*\s\)\?--\(\s.*\)\?\s))\>/
+syn match factorStackEffect /\<(\s\(\S*\s\)\?--\(\s\S*\)\?\s)\>/ contained
+syn match factorLiteralStackEffect /\<((\s\(\S*\s\)\?--\(\s\S*\)\?\s))\>/
 
 "adapted from lisp.vim
 if exists("g:factor_norainbow")