diff --git a/policy/tester.go b/policy/tester.go
index 4baae4cb2..9c2937e54 100644
--- a/policy/tester.go
+++ b/policy/tester.go
@@ -7,7 +7,6 @@ import (
 	"io/fs"
 	"maps"
 	"path/filepath"
-	"slices"
 	"sort"
 	"strings"
 
@@ -212,20 +211,7 @@ func loadPolicyModules(root fs.StatFS, filename string) (map[string]*ast.Module,
 }
 
 func compilePolicyModules(modules map[string]*ast.Module, p *Policy, fsProvider func() (fs.StatFS, func() error, error)) (*ast.Compiler, func() error, error) {
-	caps := &ast.Capabilities{
-		Builtins: builtins(),
-		Features: slices.Clone(ast.Features),
-	}
-	comp := ast.NewCompiler().WithCapabilities(caps).WithKeepModules(true)
-
-	builtinDefs := make(map[string]*ast.Builtin)
-	for _, f := range p.funcs {
-		builtinDefs[f.decl.Name] = &ast.Builtin{
-			Name: f.decl.Name,
-			Decl: f.decl.Decl,
-		}
-	}
-	comp = comp.WithBuiltins(builtinDefs)
+	comp := ast.NewCompiler().WithCapabilities(p.capabilities()).WithKeepModules(true)
 
 	loader, closeLoader := newPolicyModuleLoader(fsProvider)
 	comp = comp.WithModuleLoader(loader)
diff --git a/policy/validate.go b/policy/validate.go
index 0f8a7bfac..5bd41be4a 100644
--- a/policy/validate.go
+++ b/policy/validate.go
@@ -130,25 +130,26 @@ func (p *Policy) IsPolicyError(err error) bool {
 	return false
 }
 
-func (p *Policy) regoBaseOpts() ([]func(*rego.Rego), func(), error) {
+func (p *Policy) capabilities() *ast.Capabilities {
 	caps := &ast.Capabilities{
 		Builtins: builtins(),
 		Features: slices.Clone(ast.Features),
 	}
-	comp := ast.NewCompiler().WithCapabilities(caps).WithKeepModules(true)
+	for _, f := range p.funcs {
+		caps.Builtins = append(caps.Builtins, &ast.Builtin{
+			Name: f.decl.Name,
+			Decl: f.decl.Decl,
+		})
+	}
+	return caps
+}
+
+func (p *Policy) regoBaseOpts() ([]func(*rego.Rego), func(), error) {
+	comp := ast.NewCompiler().WithCapabilities(p.capabilities()).WithKeepModules(true)
 	if p.opt.Log != nil {
 		comp = comp.WithEnablePrintStatements(true)
 	}
 
-	builtins := make(map[string]*ast.Builtin)
-	for _, f := range p.funcs {
-		builtins[f.decl.Name] = &ast.Builtin{
-			Name: f.decl.Name,
-			Decl: f.decl.Decl,
-		}
-	}
-	comp = comp.WithBuiltins(builtins)
-
 	var root fs.StatFS
 	var closeFS func() error
 	closeRoot := func() {