diff --git a/src/main/java/dk/camelot64/kickc/passes/Pass4MemoryCoalesce.java b/src/main/java/dk/camelot64/kickc/passes/Pass4MemoryCoalesce.java
index c229e98fe..64d60f35f 100644
--- a/src/main/java/dk/camelot64/kickc/passes/Pass4MemoryCoalesce.java
+++ b/src/main/java/dk/camelot64/kickc/passes/Pass4MemoryCoalesce.java
@@ -143,6 +143,10 @@ public abstract class Pass4MemoryCoalesce extends Pass2Base {
       // Check the both registers have the same type
       if(!register1.getType().equals(register2.getType()))
          return false;
+      if(register1.toString().startsWith("mem"))
+         return false;
+      if(register2.toString().startsWith("mem"))
+         return false;
       // Check the both registers have the same size
       if(register1.getBytes() != register2.getBytes())
          return false;