diff --git a/core/embed/rust/src/ui/model_tt/component/number_input.rs b/core/embed/rust/src/ui/model_tt/component/number_input.rs
index 619583d861..c36df7ae9d 100644
--- a/core/embed/rust/src/ui/model_tt/component/number_input.rs
+++ b/core/embed/rust/src/ui/model_tt/component/number_input.rs
@@ -1,13 +1,15 @@
-use crate::ui::{
-    component::{
-        base::ComponentExt,
-        paginated::Paginate,
-        text::paragraphs::{Paragraph, ParagraphStrType, Paragraphs},
-        Child, Component, Event, EventCtx, Pad,
+use crate::{
+    strutil,
+    ui::{
+        component::{
+            base::ComponentExt,
+            paginated::Paginate,
+            text::paragraphs::{Paragraph, ParagraphStrType, Paragraphs},
+            Child, Component, Event, EventCtx, Pad,
+        },
+        display::{self, Font},
+        geometry::{Grid, Insets, Offset, Rect},
     },
-    display::{self, Font},
-    geometry::{Grid, Insets, Offset, Rect},
-    util,
 };
 
 use super::{theme, Button, ButtonMsg};
@@ -210,7 +212,7 @@ impl Component for NumberInput {
 
     fn paint(&mut self) {
         let mut buf = [0u8; 10];
-        if let Some(text) = util::u32_to_str(self.value, &mut buf) {
+        if let Some(text) = strutil::format_i64(self.value as i64, &mut buf) {
             let digit_font = Font::DEMIBOLD;
             let y_offset = digit_font.text_height() / 2 + Button::<&str>::BASELINE_OFFSET;
             display::rect_fill(self.area, theme::BG);
diff --git a/core/embed/rust/src/ui/util.rs b/core/embed/rust/src/ui/util.rs
index ae74212549..c332c5cbdc 100644
--- a/core/embed/rust/src/ui/util.rs
+++ b/core/embed/rust/src/ui/util.rs
@@ -20,26 +20,6 @@ impl<T, E> ResultExt for Result<T, E> {
     }
 }
 
-pub fn u32_to_str(num: u32, buffer: &mut [u8]) -> Option<&str> {
-    let mut i = 0;
-    let mut num = num;
-
-    while num > 0 && i < buffer.len() {
-        buffer[i] = b'0' + ((num % 10) as u8);
-        num /= 10;
-        i += 1;
-    }
-    match i {
-        0 => Some("0"),
-        _ if num > 0 => None,
-        _ => {
-            let result = &mut buffer[..i];
-            result.reverse();
-            Some(core::str::from_utf8(result).unwrap())
-        }
-    }
-}
-
 /// Constructs a string from a C string.
 ///
 /// # Safety
@@ -140,7 +120,7 @@ pub fn icon_text_center(
 
 #[cfg(test)]
 mod tests {
-    use super::*;
+    use crate::strutil;
 
     #[test]
     fn u32_to_str_valid() {
@@ -148,7 +128,7 @@ mod tests {
         let mut b = [0; 10];
 
         for test in testcases {
-            let converted = u32_to_str(test, &mut b).unwrap();
+            let converted = strutil::format_i64(test as i64, &mut b).unwrap();
             let s = test.to_string();
             assert_eq!(converted, s);
         }
@@ -160,7 +140,7 @@ mod tests {
         let mut b = [0; 3];
 
         for test in testcases {
-            let converted = u32_to_str(test, &mut b);
+            let converted = strutil::format_i64(test as i64, &mut b);
             assert_eq!(converted, None)
         }
     }