diff --git a/certora/makefile b/certora/Makefile
similarity index 67%
rename from certora/makefile
rename to certora/Makefile
index f3a1e41..ad67b39 100644
--- a/certora/makefile
+++ b/certora/Makefile
@@ -7,7 +7,7 @@ munged-simple: $(wildcard ../src/*.sol) applyHarnessSimple.patch
 	@patch -p0 -d munged-simple < applyHarnessSimple.patch
 
 record-simple:
-	diff -ruN ../src munged-simple | sed 's,\.\./src/\|munged-simple/,,g' | sed 's,\(\(\-\-\-\|+++\) [^[:space:]]*\).*,\1,' > applyHarnessSimple.patch
+	diff -ruN ../src munged-simple | sed -E 's,\.\./src/|munged-simple/,,g' | sed -E 's,((\-\-\-|\+\+\+) [^[:space:]]*).*,\1,' > applyHarnessSimple.patch
 
 munged-fifo: $(wildcard ../src/*.sol) applyHarnessFifo.patch
 	@rm -rf munged-fifo
@@ -15,7 +15,7 @@ munged-fifo: $(wildcard ../src/*.sol) applyHarnessFifo.patch
 	@patch -p0 -d munged-fifo < applyHarnessFifo.patch
 
 record-fifo:
-	diff -ruN ../src munged-fifo | sed 's,\.\./src/\|munged-fifo/,,g' | sed 's,\(\(\-\-\-\|+++\) [^[:space:]]*\).*,\1,' > applyHarnessFifo.patch
+	diff -ruN ../src munged-fifo | sed -E 's,\.\./src/|munged-fifo/,,g' | sed -E 's,((\-\-\-|\+\+\+) [^[:space:]]*).*,\1,' > applyHarnessFifo.patch
 
 clean:
 	rm -rf munged-simple munged-fifo