diff --git a/app.go b/app.go
index ba037dd41bb7..1f6447054ce4 100644
--- a/app.go
+++ b/app.go
@@ -16,6 +16,7 @@ import (
 	"cosmossdk.io/log"
 	abci "github.com/cometbft/cometbft/abci/types"
 	dbm "github.com/cosmos/cosmos-db"
+	"github.com/cosmos/gogoproto/proto"
 	"github.com/spf13/cast"
 
 	simappparams "cosmossdk.io/simapp/params"
@@ -50,6 +51,7 @@ import (
 	testdata_pulsar "github.com/cosmos/cosmos-sdk/testutil/testdata/testpb"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/types/module"
+	"github.com/cosmos/cosmos-sdk/types/msgservice"
 	"github.com/cosmos/cosmos-sdk/version"
 	"github.com/cosmos/cosmos-sdk/x/auth"
 	"github.com/cosmos/cosmos-sdk/x/auth/ante"
@@ -507,6 +509,19 @@ func NewSimApp(
 	// upgrade.
 	app.setPostHandler()
 
+	// At startup, after all modules have been registered, check that all prot
+	// annotations are correct.
+	protoFiles, err := proto.MergedRegistry()
+	if err != nil {
+		panic(err)
+	}
+	err = msgservice.ValidateProtoAnnotations(protoFiles)
+	if err != nil {
+		// Once we switch to using protoreflect-based antehandlers, we might
+		// want to panic here instead of logging a warning.
+		fmt.Fprintln(os.Stderr, err.Error())
+	}
+
 	if loadLatest {
 		if err := app.LoadLatestVersion(); err != nil {
 			panic(fmt.Errorf("error loading last version: %w", err))
diff --git a/app_test.go b/app_test.go
index 0b251a46af86..28268ab416dc 100644
--- a/app_test.go
+++ b/app_test.go
@@ -22,6 +22,7 @@ import (
 	simtestutil "github.com/cosmos/cosmos-sdk/testutil/sims"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/types/module"
+	"github.com/cosmos/cosmos-sdk/types/msgservice"
 	"github.com/cosmos/cosmos-sdk/x/auth"
 	"github.com/cosmos/cosmos-sdk/x/auth/vesting"
 	authzmodule "github.com/cosmos/cosmos-sdk/x/authz/module"
@@ -279,3 +280,10 @@ func TestMergedRegistry(t *testing.T) {
 	require.NoError(t, err)
 	require.Greater(t, r.NumFiles(), 0)
 }
+
+func TestProtoAnnotations(t *testing.T) {
+	r, err := proto.MergedRegistry()
+	require.NoError(t, err)
+	err = msgservice.ValidateProtoAnnotations(r)
+	require.NoError(t, err)
+}
diff --git a/go.mod b/go.mod
index 260d64d69a8f..aecc18c21add 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,7 @@ module cosmossdk.io/simapp
 go 1.20
 
 require (
-	cosmossdk.io/api v0.3.1
+	cosmossdk.io/api v0.3.2-0.20230313131911-55bf5d4efbe7
 	cosmossdk.io/client/v2 v2.0.0-20230309163709-87da587416ba
 	cosmossdk.io/core v0.6.1-0.20230309163709-87da587416ba
 	cosmossdk.io/depinject v1.0.0-alpha.3
@@ -194,6 +194,7 @@ require (
 // Replace here are pending PRs, or version to be tagged
 replace (
 	// TODO tag all extracted modules after SDK refactor
+	cosmossdk.io/api => ../api
 	cosmossdk.io/tools/confix => ../tools/confix
 	cosmossdk.io/tools/rosetta => ../tools/rosetta
 	cosmossdk.io/x/evidence => ../x/evidence
diff --git a/go.sum b/go.sum
index e9f583e52f80..0a61b56504f1 100644
--- a/go.sum
+++ b/go.sum
@@ -188,8 +188,6 @@ cloud.google.com/go/webrisk v1.4.0/go.mod h1:Hn8X6Zr+ziE2aNd8SliSDWpEnSS1u4R9+xX
 cloud.google.com/go/webrisk v1.5.0/go.mod h1:iPG6fr52Tv7sGk0H6qUFzmL3HHZev1htXuWDEEsqMTg=
 cloud.google.com/go/workflows v1.6.0/go.mod h1:6t9F5h/unJz41YqfBmqSASJSXccBLtD1Vwf+KmJENM0=
 cloud.google.com/go/workflows v1.7.0/go.mod h1:JhSrZuVZWuiDfKEFxU0/F1PQjmpnpcoISEXH2bcHC3M=
-cosmossdk.io/api v0.3.1 h1:NNiOclKRR0AOlO4KIqeaG6PS6kswOMhHD0ir0SscNXE=
-cosmossdk.io/api v0.3.1/go.mod h1:DfHfMkiNA2Uhy8fj0JJlOCYOBp4eWUUJ1te5zBGNyIw=
 cosmossdk.io/client/v2 v2.0.0-20230309163709-87da587416ba h1:LuPHCncU2KLMNPItFECs709uo46I9wSu2fAWYVCx+/U=
 cosmossdk.io/client/v2 v2.0.0-20230309163709-87da587416ba/go.mod h1:SXdwqO7cN5htalh/lhXWP8V4zKtBrhhcSTU+ytuEtmM=
 cosmossdk.io/collections v0.0.0-20230309163709-87da587416ba h1:S4PYij/tX3Op/hwenVEN9D+M27JRcwSwVqE3UA0BnwM=