diff --git a/src/zscript/vmbuilder.cpp b/src/zscript/vmbuilder.cpp
index fd01190553..3f1757828f 100644
--- a/src/zscript/vmbuilder.cpp
+++ b/src/zscript/vmbuilder.cpp
@@ -427,6 +427,14 @@ size_t VMFunctionBuilder::Emit(int opcode, int opa, int opb, int opc)
 	code[1] = opa;
 	code[2] = opb;
 	code[3] = opc;
+	if (opcode == OP_PARAM)
+	{
+		ParamChange(1);
+	}
+	else if (opcode == OP_CALL || opcode == OP_CALL_K)
+	{
+		ParamChange(-opb);
+	}
 	return loc / 4;
 }
 
diff --git a/src/zscript/vmbuilder.h b/src/zscript/vmbuilder.h
index af43cbf8b6..a1c6dfe3f3 100644
--- a/src/zscript/vmbuilder.h
+++ b/src/zscript/vmbuilder.h
@@ -47,9 +47,6 @@ public:
 	void FillAddressConstants(FVoidObj *konst, VM_ATAG *tags);
 	void FillStringConstants(FString *strings);
 
-	// PARAM increases ActiveParam; CALL decreases it.
-	void ParamChange(int delta);
-
 	// Track available registers.
 	RegAvailability Registers[4];
 
@@ -77,6 +74,9 @@ private:
 	int ActiveParam;
 
 	TArray<VM_UBYTE> Code;
+
+	// PARAM increases ActiveParam; CALL decreases it.
+	void ParamChange(int delta);
 };
 
 #endif