diff --git a/backends/btor/btor.cc b/backends/btor/btor.cc
index 965d4aa4..f5babebc 100644
--- a/backends/btor/btor.cc
+++ b/backends/btor/btor.cc
@@ -30,7 +30,6 @@
 #include <string>
 #include <assert.h>
 #include <math.h>
-#include <regex>
 
 struct BtorDumperConfig
 {