diff --git a/libs/core/core.cpp b/libs/core/core.cpp
index 1dabda5f..a4d083da 100644
--- a/libs/core/core.cpp
+++ b/libs/core/core.cpp
@@ -224,7 +224,8 @@ namespace pxt {
   uint32_t afterProgramPage() {
     uint32_t ptr = (uint32_t)&bytecode[0];
     ptr += programSize();
-    ptr = (ptr + (PAGE_SIZE - 1)) & ~(PAGE_SIZE - 1);
+    if (ptr % PAGE_SIZE != 0)
+      ptr = (ptr & ~(PAGE_SIZE-1)) + PAGE_SIZE;
     return ptr;
   }
 }