diff --git a/Makefile b/Makefile
index acb33bcf6318b50822a3be46835b15c406a4a16d..51dbeaf19f0e7ea9e57fd7c080eaaa3c769fbd22 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
-.PHONY: all generate
+.PHONY: all generate test
 
-all: generate
+all: generate test
 	test -d bin || mkdir bin
 	go build -o ./bin ./...
 
@@ -12,5 +12,8 @@ api/endpoints.go: api/oapi-config.yaml api/units.yaml
 	OAPI_CODEGEN=$(OAPI_CODEGEN) \
 	  go generate api/generate.go
 
+test:
+	go test ./...
+
 # vim:ft=make
 #
diff --git a/rules/rules.go b/rules/rules.go
index 0315113e54e817c1ba4d0e2597a05c5b4c37377d..c0bb7684ac67aea5a0bd736624ae8f6e2fc1fd6c 100644
--- a/rules/rules.go
+++ b/rules/rules.go
@@ -28,7 +28,7 @@ func New() (*Engine, error) {
 		return nil, err
 	}
 
-	rules, err := src.ReadFile("source/rules.pdb")
+	rules, err := src.ReadFile("source/rules.pl")
 	if err != nil {
 		return nil, err
 	}
diff --git a/rules/source/rules.pdb b/rules/source/rules.pl
old mode 100644
new mode 100755
similarity index 98%
rename from rules/source/rules.pdb
rename to rules/source/rules.pl
index c9c10c6012dc03a975dadf382d1961dc2c81d8ec..cc55c8e91d3d3e3eb394b8088a78851886c29bf5
--- a/rules/source/rules.pdb
+++ b/rules/source/rules.pl
@@ -1,3 +1,5 @@
+% vim: set ft=prolog:
+
 unit_kind(f, temperature).
 unit_kind(k, temperature).
 unit_kind(c, temperature).