diff --git a/.github/workflows/check.yaml b/.github/workflows/check.yaml
index 3565c11..8ff6375 100644
--- a/.github/workflows/check.yaml
+++ b/.github/workflows/check.yaml
@@ -15,5 +15,8 @@ jobs:
     - name: OPA check strict
       run: opa check --strict test/
 
-    - name: Check formatting
-      run: opa fmt --diff --fail test/
+    - name: Setup Regal
+      uses: StyraInc/setup-regal@v0.2.0
+      with:
+        version: latest
+    - run: regal lint --format github test/
diff --git a/.regal/config.yaml b/.regal/config.yaml
new file mode 100644
index 0000000..bbc3b43
--- /dev/null
+++ b/.regal/config.yaml
@@ -0,0 +1,7 @@
+rules:
+  idiomatic:
+    no-defined-entrypoint:
+      level: ignore
+  testing:
+    print-or-trace-call:
+      level: ignore
diff --git a/test/assert.rego b/test/assert.rego
index e903f39..aa4e01f 100644
--- a/test/assert.rego
+++ b/test/assert.rego
@@ -6,151 +6,150 @@
 package test.assert
 
 import future.keywords.every
+import future.keywords.if
 import future.keywords.in
 
 # METADATA
 # description: Assert expected is equal to result
-equals(expected, result) {
+equals(expected, result) if {
 	expected == result
-} else := false {
+} else := false if {
 	print("expected equals:", _quote_str(expected), "got:", result)
 }
 
 # METADATA
 # description: Assert expected is not equal to result
-not_equals(expected, result) {
+not_equals(expected, result) if {
 	expected != result
-} else := false {
+} else := false if {
 	print("expected not equals:", _quote_str(expected), "got:", result)
 }
 
 # METADATA
 # description: Assert all items in coll are equal to value
-all_equals(coll, value) {
+all_equals(coll, value) if {
 	every item in coll {
 		item == value
 	}
-} else := false {
+} else := false if {
 	exceptions := [item | some item in coll; item != value]
 	print("expected all items to have value", _append_comma(value), "failed for", exceptions)
 }
 
 # METADATA
 # description: Assert no items in coll are equal to value
-none_equals(coll, value) {
+none_equals(coll, value) if {
 	every item in coll {
 		item != value
 	}
-} else := false {
+} else := false if {
 	exceptions := [item | some item in coll; item == value]
 	print("expected no items to have value", _append_comma(value), "failed for", exceptions)
 }
 
 # METADATA
 # description: Assert item is in coll
-has(item, coll) {
+has(item, coll) if {
 	item in coll
-} else := false {
+} else := false if {
 	print("expected", type_name(item), _quote_str(item), "in", type_name(coll), "got:", coll)
 }
 
 # METADATA
 # description: Assert item is not in coll
-not_has(item, coll) {
+not_has(item, coll) if {
 	not item in coll
-} else := false {
+} else := false if {
 	print("expected", type_name(item), _quote_str(item), "not in", type_name(coll), "got:", coll)
 }
 
 # METADATA
 # description: Assert provided collection is empty
-empty(coll) {
+empty(coll) if {
 	count(coll) == 0
-} else := false {
+} else := false if {
 	print("expected empty", type_name(coll), "got:", coll)
 }
 
 # METADATA
 # description: Assert provided collection is not empty
-not_empty(coll) {
+not_empty(coll) if {
 	count(coll) != 0
-} else := false {
+} else := false if {
 	print("expected not empty", type_name(coll))
 }
 
 # METADATA
 # description: Assert string starts with search
-starts_with(str, search) {
+starts_with(str, search) if {
 	startswith(str, search)
-} else := false {
+} else := false if {
 	print("expected", _quote_str(str), "to start with", _quote_str(search))
 }
 
 # METADATA
 # description: Assert string ends with search
-ends_with(str, search) {
+ends_with(str, search) if {
 	endswith(str, search)
-} else := false {
+} else := false if {
 	print("expected", _quote_str(str), "to end with", _quote_str(search))
 }
 
 # METADATA
 # description: Assert all strings in coll starts with search
-all_starts_with(coll, search) {
+all_starts_with(coll, search) if {
 	every str in coll {
 		startswith(str, search)
 	}
-} else := false {
+} else := false if {
 	exceptions := [str | some str in coll; not startswith(str, search)]
 	print("expected all strings to start with", _append_comma(search), "failed for", exceptions)
 }
 
 # METADATA
 # description: Assert all strings in coll ends with search
-all_ends_with(coll, search) {
+all_ends_with(coll, search) if {
 	every str in coll {
 		endswith(str, search)
 	}
-} else := false {
+} else := false if {
 	exceptions := [str | some str in coll; not endswith(str, search)]
 	print("expected all strings to end with", _append_comma(search), "failed for", exceptions)
 }
 
 # METADATA
 # description: Assert no strings in coll starts with search
-none_starts_with(coll, search) {
+none_starts_with(coll, search) if {
 	every str in coll {
 		not startswith(str, search)
 	}
-} else := false {
+} else := false if {
 	exceptions := [str | some str in coll; startswith(str, search)]
 	print("expected no strings to start with", _append_comma(search), "failed for", exceptions)
 }
 
 # METADATA
 # description: Assert no strings in coll ends with search
-none_ends_with(coll, search) {
+none_ends_with(coll, search) if {
 	every str in coll {
 		not endswith(str, search)
 	}
-} else := false {
+} else := false if {
 	exceptions := [str | some str in coll; endswith(str, search)]
 	print("expected no strings to end with", _append_comma(search), "failed for", exceptions)
 }
 
 # METADATA
 # description: Fail with provided message
-fail(msg) {
+fail(msg) if {
 	print(msg)
+
+	# regal ignore:constant-condition
 	false
 }
 
-_quote_str(x) := concat("", [`"`, x, `"`]) {
-	is_string(x)
-}
+_quote_str(x) := concat("", [`"`, x, `"`]) if is_string(x)
 
-_quote_str(x) := x {
-	not is_string(x)
-}
+_quote_str(x) := x if not is_string(x)
 
 _append_comma(str) := sprintf("%v,", [_quote_str(str)])