diff --git a/syntax/maude.vim b/syntax/maude.vim
index 8d4b432..23c6b62 100644
--- a/syntax/maude.vim
+++ b/syntax/maude.vim
@@ -82,8 +82,8 @@ syn match maudeQid /''\?\S\+/
 syn match maudeQid /'"\%([^"\\]\|\\.\)*"/ contains=maudeStringEsc
 hi def link maudeQid Constant
 
-syn match maudeNum !-\?\d\+\%(/\d\+\)\?!
-syn match maudeNum /-\?\d\+\.\d\+\%([Ee][+-]\?\d\+\)\?/
+syn match maudeNum !\%(^\|\s\)\zs-\?\d\+\%(/\d\+\)\?\ze\%(\s\|$\)!
+syn match maudeNum /\%(^\|\s\)\zs-\?\d\+\.\d\+\%([Ee][+-]\?\d\+\)\?\ze\%(\s\|$\)/
 syn keyword maudeNum Infinity -Infinity
 hi def link maudeNum Number