diff --git a/src/test/ddnf.cpp b/src/test/ddnf.cpp
index 8620bd441..d2ca92557 100644
--- a/src/test/ddnf.cpp
+++ b/src/test/ddnf.cpp
@@ -123,7 +123,7 @@ datalog::ddnf_core* populate_ddnf(char const* file, ptr_vector<tbv>& tbvs) {
 
 
 static void read_args(char ** argv, int argc, int& i) {
-    if (argc = i + 2) {
+    if (argc == i + 2) {
         g_file = argv[i + 1];
         ++i;
         return;