diff --git a/latexdiff b/latexdiff
index 01c5684..b365c9c 100755
--- a/latexdiff
+++ b/latexdiff
@@ -2576,9 +2576,9 @@ sub take_comments_and_newline_from_frac() {
   # \frac1 -> \frac{1}
   # \frac a -> \frac{a}
   # \frac \lambda -> \frac{\lambda}
-  s/\\frac(?:${space}+\{($pat_n)\}|${space}*(\d)|${space}+(\w)|${space}*(\\[a-zA-Z]+))/\\frac\{$1$2$3$4\}/g;
+  s/\\frac(?|${space}+\{($pat_n)\}|${space}*(\d)|${space}+(\w)|${space}*(\\[a-zA-Z]+))/\\frac\{$1\}/g;
   # same as above for the second argument of frac
-  s/\\frac(\{$pat_n\})(?:${space}*\{($pat_n)\}|${space}*(\d)|${space}+(\w)|${space}*(\\[a-zA-Z]+))/\\frac$1\{$2$3$4$5\}/g;
+  s/\\frac(\{$pat_n\})(?|${space}*\{($pat_n)\}|${space}*(\d)|${space}+(\w)|${space}*(\\[a-zA-Z]+))/\\frac$1\{$2\}/g;
 }
 
 # preprocess($string, ..)