diff --git a/Makefile b/Makefile
index a0d8576..d3a6a64 100644
--- a/Makefile
+++ b/Makefile
@@ -5,6 +5,7 @@ BINS = $(wildcard bin/git-*)
 MANS = $(wildcard man/git-*.md)
 MAN_HTML = $(MANS:.md=.html)
 MAN_PAGES = $(MANS:.md=.1)
+LIB = "helper/git-extra-utility"
 
 COMMANDS_USED_WITHOUT_GIT_REPO = git-alias git-extras git-fork git-setup
 COMMANDS_USED_WITH_GIT_REPO = $(filter-out $(COMMANDS_USED_WITHOUT_GIT_REPO), \
@@ -22,13 +23,15 @@ install:
 	@chmod 775 $(TEMPFILE)
 	@$(foreach COMMAND, $(COMMANDS_USED_WITH_GIT_REPO), \
 		echo "... installing $(COMMAND)"; \
-		head -1 bin/$(COMMAND) | cat - ./helper/is-git-repo > $(TEMPFILE); \
+		head -1 bin/$(COMMAND) | cat - $(LIB) ./helper/is-git-repo > $(TEMPFILE); \
 		tail -n +2 bin/$(COMMAND) >> $(TEMPFILE); \
 		cp -f $(TEMPFILE) $(DESTDIR)$(BINPREFIX)/$(COMMAND); \
 	)
 	@$(foreach COMMAND, $(COMMANDS_USED_WITHOUT_GIT_REPO), \
 		echo "... installing $(COMMAND)"; \
-		cp -f bin/$(COMMAND) $(DESTDIR)$(BINPREFIX); \
+		head -1 bin/$(COMMAND) | cat - $(LIB) > $(TEMPFILE); \
+		tail -n +2 bin/$(COMMAND) >> $(TEMPFILE); \
+		cp -f $(TEMPFILE) $(DESTDIR)$(BINPREFIX)/$(COMMAND); \
 	)
 	@if [ -z "$(wildcard man/git-*.1)" ]; then \
 		echo "WARNING: man pages not created, use 'make docs' (which requires 'ronn' ruby lib)"; \
diff --git a/bin/git-changelog b/bin/git-changelog
index 096d732..d2b2639 100755
--- a/bin/git-changelog
+++ b/bin/git-changelog
@@ -47,7 +47,7 @@ if test "$CHANGELOG" = ""; then
     CHANGELOG='History.md';
   fi
 fi
-tmp=`mktemp -t $(basename $0).XXX`
+tmp=$(git_extra_mktemp)
 printf "$HEAD" > $tmp
 git-changelog $GIT_LOG_OPTS --list >> $tmp
 printf '\n\n' >> $tmp
diff --git a/bin/git-effort b/bin/git-effort
index 6da4f79..4fb2981 100755
--- a/bin/git-effort
+++ b/bin/git-effort
@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 
-tmp=`mktemp -t $(basename $0)`
+tmp=$(git_extra_mktemp)
 above='0'
 color=
 
diff --git a/bin/git-rebase-patch b/bin/git-rebase-patch
index 6e7681e..0835052 100755
--- a/bin/git-rebase-patch
+++ b/bin/git-rebase-patch
@@ -15,7 +15,7 @@ then
 fi
 
 # Use a temporary index.
-index=`mktemp -t $(basename $0)`
+index=$(git_extra_mktemp)
 cleanup() {
         rm $index
         exit 2
diff --git a/helper/git-extra-utility b/helper/git-extra-utility
new file mode 100755
index 0000000..98ed09f
--- /dev/null
+++ b/helper/git-extra-utility
@@ -0,0 +1,7 @@
+# put all utility functions here
+
+# make a temporary file
+git_extra_mktemp() {
+    mktemp -t "$(basename "$0")".XXX
+}
+