diff --git a/lang/tcl87/Makefile b/lang/tcl87/Makefile
index 4d9ce8770456..26d028db6aae 100644
--- a/lang/tcl87/Makefile
+++ b/lang/tcl87/Makefile
@@ -17,6 +17,8 @@ LICENSE_NAME=	Tcl/Tk License
 LICENSE_FILE=	${WRKSRC}/../license.terms
 LICENSE_PERMS=	dist-mirror dist-sell pkg-mirror pkg-sell auto-accept
 
+LIB_DEPENDS=		libtommath.so:math/libtommath
+
 USES=		compiler:c11 pathfix
 
 OPTIONS_DEFINE=	TCLMAN TZDATA DEBUG