diff --git a/.changeset/funny-donkeys-destroy.md b/.changeset/funny-donkeys-destroy.md
new file mode 100644
index 00000000000..0f2d69c411d
--- /dev/null
+++ b/.changeset/funny-donkeys-destroy.md
@@ -0,0 +1,5 @@
+---
+'@itwin/itwinui-react': patch
+---
+
+Fixed rare bug where icons in button components (e.g. `Button`, `SidenavButton`, etc.) were becoming 0 in width when less space was available.
diff --git a/packages/itwinui-css/src/button/base.scss b/packages/itwinui-css/src/button/base.scss
index e6e9ea17d8c..0c916eb51ed 100644
--- a/packages/itwinui-css/src/button/base.scss
+++ b/packages/itwinui-css/src/button/base.scss
@@ -40,6 +40,7 @@ $disabledButtonSelectors: '[disabled], :disabled, [aria-disabled="true"], [data-
 
 @mixin iui-button-icon {
   display: inline-flex;
+  flex-shrink: 0;
 
   svg {
     @include mixins.iui-icon-style('m');