diff --git a/.changeset/five-rockets-battle.md b/.changeset/five-rockets-battle.md
new file mode 100644
index 000000000..46b50005b
--- /dev/null
+++ b/.changeset/five-rockets-battle.md
@@ -0,0 +1,5 @@
+---
+"@react-pdf/textkit": patch
+---
+
+fix: cannot read units for Em
diff --git a/packages/textkit/src/engines/fontSubstitution/index.ts b/packages/textkit/src/engines/fontSubstitution/index.ts
index 2116a4317..5897be0be 100644
--- a/packages/textkit/src/engines/fontSubstitution/index.ts
+++ b/packages/textkit/src/engines/fontSubstitution/index.ts
@@ -65,7 +65,7 @@ const fontSubstitution =
         if (
           font !== lastFont ||
           fontSize !== lastFontSize ||
-          font.unitsPerEm !== lastFont.unitsPerEm
+         font.unitsPerEm !== lastFont?.unitsPerEm
         ) {
           if (lastFont) {
             res.push({