diff --git a/poppler/Function.cc b/poppler/Function.cc
index 25e8f74..01c5ff7 100644
--- a/poppler/Function.cc
+++ b/poppler/Function.cc
@@ -1010,6 +1010,10 @@ public:
       return;
     }
     --sp;
+    if (sp + i + 1 >= psStackSize) {
+      error(errSyntaxError, -1, "Stack underflow in PostScript function");
+      return;
+    }
     stack[sp] = stack[sp + 1 + i];
   }
   void pop()