diff --git a/events/codebuild.go b/events/codebuild.go
index 08cbb607..22e2d5db 100644
--- a/events/codebuild.go
+++ b/events/codebuild.go
@@ -205,12 +205,12 @@ type CodeBuildNumber int32
 
 // MarshalJSON converts a given CodeBuildNumber to json
 func (n CodeBuildNumber) MarshalJSON() ([]byte, error) {
-	return json.Marshal(float32(n))
+	return json.Marshal(float64(n))
 }
 
 // UnmarshalJSON converts a given json to a CodeBuildNumber
 func (n *CodeBuildNumber) UnmarshalJSON(data []byte) error {
-	var f float32
+	var f float64
 	if err := json.Unmarshal(data, &f); err != nil {
 		return err
 	}
diff --git a/events/codebuild_test.go b/events/codebuild_test.go
index 6d25c1fb..c30372c9 100644
--- a/events/codebuild_test.go
+++ b/events/codebuild_test.go
@@ -310,3 +310,19 @@ func TestUnmarshalCodeBuildEvent(t *testing.T) {
 		require.Equal(t, testcase.expect, actual)
 	}
 }
+
+func TestCodeBuildNumberKeepsEveryInt32(t *testing.T) {
+	// 16777217 is 2^24+1, the first integer a float32 cannot hold.
+	for _, want := range []CodeBuildNumber{1, 16777217, 2147483647} {
+		b, err := json.Marshal(want)
+		require.NoError(t, err)
+
+		var got CodeBuildNumber
+		require.NoError(t, json.Unmarshal(b, &got))
+		require.Equal(t, want, got)
+	}
+
+	var got CodeBuildNumber
+	require.NoError(t, json.Unmarshal([]byte("16777217"), &got))
+	require.Equal(t, CodeBuildNumber(16777217), got)
+}