diff --git a/.gitignore b/.gitignore
index 17fe96d..f91f2e1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,4 @@
 src/secretkey.h
 src/secretkey.bin
 src/genkey
-src/exim-kitencrypt-dlfunc.so
+src/libexim-kitencrypt-dlfunc.so
diff --git a/src/Makefile b/src/Makefile
index dd2c27d..ee548c2 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -1,5 +1,9 @@
-exim-kitencrypt-dlfunc.so: exim-kitencrypt-dlfunc.c exim-kitencrypt-dlfunc.h secretkey.h
-	gcc exim-kitencrypt-dlfunc.c -fPIC -fpic -shared -I/usr/include/exim4 -export-dynamic -o exim-kitencrypt-dlfunc.so
+.PHONY: clean
+
+.DEFAULT_GOAL := libexim-kitencrypt-dlfunc.so
+
+libexim-kitencrypt-dlfunc.so: libexim-kitencrypt-dlfunc.c libexim-kitencrypt-dlfunc.h secretkey.h
+	gcc libexim-kitencrypt-dlfunc.c -fpic -shared -I/usr/include/exim4 -lsodium -export-dynamic -o libexim-kitencrypt-dlfunc.so
 
 genkey: genkey.c
 	gcc -lsodium -o genkey genkey.c
@@ -8,3 +12,6 @@ secretkey.h: secretkey.bin
 
 secretkey.bin: genkey
 	./genkey
+
+clean:
+	rm -f libexim-kitencrypt-dlfunc.so
diff --git a/src/exim-kitencrypt-dlfunc.c b/src/libexim-kitencrypt-dlfunc.c
similarity index 96%
rename from src/exim-kitencrypt-dlfunc.c
rename to src/libexim-kitencrypt-dlfunc.c
index 1c39102..d4b59c7 100644
--- a/src/exim-kitencrypt-dlfunc.c
+++ b/src/libexim-kitencrypt-dlfunc.c
@@ -1,8 +1,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <strings.h>
-#include "exim-kitencrypt-dlfunc.h"
 #include "secretkey.h"
+#include <sodium.h>
+#include <local_scan.h>
 
 int kitencrypt(uschar **yield, int argc, uschar *argv[]) {
 	int sinit;
diff --git a/src/exim-kitencrypt-dlfunc.h b/src/libexim-kitencrypt-dlfunc.h
similarity index 60%
rename from src/exim-kitencrypt-dlfunc.h
rename to src/libexim-kitencrypt-dlfunc.h
index 94b2c1a..d038604 100644
--- a/src/exim-kitencrypt-dlfunc.h
+++ b/src/libexim-kitencrypt-dlfunc.h
@@ -1,9 +1,7 @@
-#include <sodium.h>
-#include <local_scan.h>
-
 #ifndef EXIM_ENCRYPT_LIBRARY_H
 #define EXIM_ENCRYPT_LIBRARY_H
 
+extern int kitencrypt(uschar **yield, int argc, uschar *argv[]);
 
 #endif //EXIM_ENCRYPT_LIBRARY_H