diff --git a/WORKSPACE b/WORKSPACE
index e2bc9580..86d3c57e 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -119,7 +119,7 @@ go_repository(
 # CEL Spec deps
 go_repository(
     name = "com_google_cel_spec",
-    commit = "1bc3fb168317fa77d1227c52d0becbf2d358c023",
+    commit = "91f3cb1a7590f594a392b607ae9cab5e969b4cf3",
     importpath = "github.com/google/cel-spec",
 )
 
diff --git a/conformance/BUILD.bazel b/conformance/BUILD.bazel
index dc78a024..e1fd8b9b 100644
--- a/conformance/BUILD.bazel
+++ b/conformance/BUILD.bazel
@@ -10,6 +10,7 @@ ALL_TESTS = [
     "@com_google_cel_spec//tests/simple:testdata/lists.textproto",
     "@com_google_cel_spec//tests/simple:testdata/logic.textproto",
     "@com_google_cel_spec//tests/simple:testdata/macros.textproto",
+    "@com_google_cel_spec//tests/simple:testdata/math_ext.textproto",
     "@com_google_cel_spec//tests/simple:testdata/namespace.textproto",
     "@com_google_cel_spec//tests/simple:testdata/optionals.textproto",
     "@com_google_cel_spec//tests/simple:testdata/parse.textproto",
@@ -17,6 +18,7 @@ ALL_TESTS = [
     "@com_google_cel_spec//tests/simple:testdata/proto2.textproto",
     "@com_google_cel_spec//tests/simple:testdata/proto3.textproto",
     "@com_google_cel_spec//tests/simple:testdata/string.textproto",
+    "@com_google_cel_spec//tests/simple:testdata/string_ext.textproto",
     "@com_google_cel_spec//tests/simple:testdata/timestamps.textproto",
     "@com_google_cel_spec//tests/simple:testdata/unknowns.textproto",
     "@com_google_cel_spec//tests/simple:testdata/wrappers.textproto",
@@ -37,6 +39,7 @@ sh_test(
         # Failing conformance tests.
         "--skip_test=fields/qualified_identifier_resolution/map_key_float,map_key_null,map_value_repeat_key",
         "--skip_test=fields/qualified_identifier_resolution/map_value_repeat_key_heterogeneous",
+        "--skip_test=macros/map/map_extract_keys",
         "--skip_test=timestamps/duration_converters/get_milliseconds",
 
         # Future enhancments.
diff --git a/server/BUILD.bazel b/server/BUILD.bazel
index a0ff2e4a..f501d5be 100644
--- a/server/BUILD.bazel
+++ b/server/BUILD.bazel
@@ -15,6 +15,7 @@ go_library(
         "//cel:go_default_library",
         "//common/types:go_default_library",
         "//common/types/ref:go_default_library",
+        "//ext:go_default_library",
         "@com_google_cel_spec//proto/test/v1/proto2:test_all_types_go_proto",
         "@com_google_cel_spec//proto/test/v1/proto3:test_all_types_go_proto",
         "@org_golang_google_genproto_googleapis_api//expr/conformance/v1alpha1:go_default_library",
diff --git a/server/server.go b/server/server.go
index b20b52d3..7a4bb02a 100644
--- a/server/server.go
+++ b/server/server.go
@@ -22,6 +22,7 @@ import (
 	"github.com/google/cel-go/cel"
 	"github.com/google/cel-go/common/types"
 	"github.com/google/cel-go/common/types/ref"
+	"github.com/google/cel-go/ext"
 
 	test2pb "github.com/google/cel-spec/proto/test/v1/proto2/test_all_types"
 	test3pb "github.com/google/cel-spec/proto/test/v1/proto3/test_all_types"
@@ -41,7 +42,11 @@ func (s *ConformanceServer) Parse(ctx context.Context, in *confpb.ParseRequest)
 		return nil, invalidArgument("No source code.")
 	}
 	// NOTE: syntax_version isn't currently used
-	var parseOptions []cel.EnvOption
+	parseOptions := []cel.EnvOption{
+		ext.Math(),
+		ext.Protos(),
+		ext.Bindings(),
+	}
 	if in.DisableMacros {
 		parseOptions = append(parseOptions, cel.ClearMacros())
 	}
@@ -68,7 +73,12 @@ func (s *ConformanceServer) Check(ctx context.Context, in *confpb.CheckRequest)
 		return nil, invalidArgument("No source info.")
 	}
 	// Build the environment.
-	var checkOptions []cel.EnvOption = []cel.EnvOption{cel.StdLib()}
+	checkOptions := []cel.EnvOption{
+		cel.StdLib(),
+		ext.Strings(),
+		ext.Math(),
+		ext.Encoders(),
+	}
 	if in.NoStdEnv {
 		checkOptions = []cel.EnvOption{}
 	}
@@ -255,6 +265,9 @@ var evalEnv *cel.Env
 
 func init() {
 	evalEnv, _ = cel.NewEnv(
+		ext.Strings(),
+		ext.Math(),
+		ext.Encoders(),
 		cel.Types(&test2pb.TestAllTypes{}, &test3pb.TestAllTypes{}),
 		cel.EagerlyValidateDeclarations(true),
 		cel.OptionalTypes())