diff --git a/libm/freebsd-compat.h b/libm/freebsd-compat.h
index 0bcc40d..f400f2a 100644
--- a/libm/freebsd-compat.h
+++ b/libm/freebsd-compat.h
@@ -16,6 +16,8 @@
 
 #pragma once
 
+// Some FreeBSD source includes <complex.h> and assumes <math.h> from that.
+#include <math.h>
 #include <float.h>
 
 #define __weak_reference(sym,alias)     \