diff --git a/extensions/sdktools/vcallbuilder.cpp b/extensions/sdktools/vcallbuilder.cpp
index fbaadd9b..f2bfd9bf 100644
--- a/extensions/sdktools/vcallbuilder.cpp
+++ b/extensions/sdktools/vcallbuilder.cpp
@@ -1,6 +1,15 @@
 #include "vcallbuilder.h"
 #include "extension.h"
 
+ValveCall::ValveCall()
+{
+	call = NULL;
+	vparams = NULL;
+	retinfo = NULL;
+	thisinfo = NULL;
+	retbuf = NULL;
+}
+
 ValveCall::~ValveCall()
 {
 	while (!stk.empty())
diff --git a/extensions/sdktools/vcallbuilder.h b/extensions/sdktools/vcallbuilder.h
index 43322636..9f2a2255 100644
--- a/extensions/sdktools/vcallbuilder.h
+++ b/extensions/sdktools/vcallbuilder.h
@@ -23,6 +23,7 @@ struct ValveCall
 
 	unsigned char *stk_get();
 	void stk_put(unsigned char *ptr);
+	ValveCall();
 	~ValveCall();
 };