diff --git a/src/p_test.cpp b/src/p_test.cpp
index 2c4ebf57f..beb85626b 100644
--- a/src/p_test.cpp
+++ b/src/p_test.cpp
@@ -30,9 +30,10 @@ void P_TestLine(line_t* ld)
 	g_lines.emplace_back(ld);
 }
 
+extern "C" consvar_t cv_showgremlins;
+
 line_t* P_SweepTestLines(fixed_t ax, fixed_t ay, fixed_t bx, fixed_t by, fixed_t r, vector2_t* return_normal)
 {
-	extern consvar_t cv_showgremlins;
 
 	using namespace srb2::math;
 	using namespace srb2::sweep;