diff --git a/dlls/engine/entity.cpp b/dlls/engine/entity.cpp
index 9b51df6b..afb3b891 100755
--- a/dlls/engine/entity.cpp
+++ b/dlls/engine/entity.cpp
@@ -47,7 +47,7 @@ static cell AMX_NATIVE_CALL call_think(AMX *amx, cell *params)
 {
 	int iEnt = params[1];
 
-	if (is_ent_valid(iEnt)) {
+	if (!is_ent_valid(iEnt)) {
 		EngineError(amx, "Invalid Entity %d", iEnt);
 		return 0;
 	}