diff --git a/arbos/programs/api.go b/arbos/programs/api.go
index cd2143f5d0..a622f55397 100644
--- a/arbos/programs/api.go
+++ b/arbos/programs/api.go
@@ -4,6 +4,8 @@
 package programs
 
 import (
+	"strconv"
+
 	"github.com/holiman/uint256"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -265,7 +267,7 @@ func newApiClosures(
 		original := input
 
 		crash := func(reason string) {
-			panic("bad API call reason: " + reason + " request: " + string(req) + " len: " + string(len(original)) + " remaining: " + string(len(input)))
+			panic("bad API call reason: " + reason + " request: " + strconv.Itoa(int(req)) + " len: " + strconv.Itoa(len(original)) + " remaining: " + strconv.Itoa(len(input)))
 		}
 		takeInput := func(needed int, reason string) []byte {
 			if len(input) < needed {
@@ -413,7 +415,7 @@ func newApiClosures(
 			captureHostio(name, args, outs, startInk, endInk)
 			return []byte{}, nil, 0
 		default:
-			panic("unsupported call type: " + string(req))
+			panic("unsupported call type: " + strconv.Itoa(int(req)))
 		}
 	}
 }
diff --git a/arbos/programs/native_api.go b/arbos/programs/native_api.go
index bf9cda658d..ad8cc0477b 100644
--- a/arbos/programs/native_api.go
+++ b/arbos/programs/native_api.go
@@ -25,6 +25,7 @@ import "C"
 
 import (
 	"runtime"
+	"strconv"
 	"sync"
 	"sync/atomic"
 
@@ -68,11 +69,11 @@ func newApi(
 func getApi(id usize) NativeApi {
 	any, ok := apiObjects.Load(uintptr(id))
 	if !ok {
-		panic("failed to load stylus Go API id: " + string(id))
+		panic("failed to load stylus Go API id: " + strconv.Itoa(int(id)))
 	}
 	api, ok := any.(NativeApi)
 	if !ok {
-		panic("wrong type for stylus Go API id: " + string(id))
+		panic("wrong type for stylus Go API id: " + strconv.Itoa(int(id)))
 	}
 	return api
 }
diff --git a/precompiles/precompile.go b/precompiles/precompile.go
index f34c418313..7ca9d409c6 100644
--- a/precompiles/precompile.go
+++ b/precompiles/precompile.go
@@ -751,7 +751,7 @@ func (p *Precompile) Call(
 		reflectArgs = append(reflectArgs, reflect.ValueOf(evm))
 		reflectArgs = append(reflectArgs, reflect.ValueOf(value))
 	default:
-		panic("Unknown state mutability " + string(method.purity))
+		panic("Unknown state mutability " + strconv.Itoa(int(method.purity)))
 	}
 
 	args, err := method.template.Inputs.Unpack(input[4:])