diff --git a/math/Makefile b/math/Makefile
index fab655259b3c..5ffb5cae6a85 100644
--- a/math/Makefile
+++ b/math/Makefile
@@ -1033,6 +1033,7 @@
     SUBDIR += tetgen
     SUBDIR += teyjus
     SUBDIR += timbl
+    SUBDIR += tiny-bignum-c
     SUBDIR += tmv
     SUBDIR += tomsfastmath
     SUBDIR += topaz
diff --git a/math/tiny-bignum-c/Makefile b/math/tiny-bignum-c/Makefile
new file mode 100644
index 000000000000..e664bcdf80fd
--- /dev/null
+++ b/math/tiny-bignum-c/Makefile
@@ -0,0 +1,40 @@
+PORTNAME=	tiny-bignum-c
+DISTVERSION=	g20210222
+CATEGORIES=	math
+
+MAINTAINER=	yuri@FreeBSD.org
+COMMENT=	Small portable multiple-precision unsigned integer arithmetic in C
+
+LICENSE=	UNLICENSE
+LICENSE_FILE=	${WRKSRC}/LICENSE
+
+USES=		python:build,test # build only for BINARY_ALIAS
+USE_LDCONFIG=	yes
+
+USE_GITHUB=	yes
+GH_ACCOUNT=	kokke
+GH_TAGNAME=	201fb20
+
+ENAME=		bignum # libbn.so is used by another package, so install it as bignum
+
+TEST_TARGET=	all test # some tests fail, see https://github.com/kokke/tiny-bignum-c/issues/29
+
+BINARY_ALIAS=	python=${PYTHON_CMD}
+
+PLIST_FILES=	include/${ENAME}.h \
+		lib/lib${ENAME}.a \
+		lib/lib${ENAME}.so
+
+do-build:
+	@cd ${WRKSRC} && \
+		${SETENV} ${MAKE_ENV} ${CC} -c ${CFLAGS} bn.c && \
+		${AR} -cq lib${ENAME}.a bn.o && \
+		${SETENV} ${MAKE_ENV} ${CC} -c ${CFLAGS} -fPIC bn.c && \
+		${CC} -shared -o lib${ENAME}.so -Wl,-soname,lib${ENAME}.so ${LDFLAGS} bn.o
+
+do-install:
+	${INSTALL_DATA} ${WRKSRC}/bn.h ${STAGEDIR}${PREFIX}/include/${ENAME}.h
+	${INSTALL_DATA} ${WRKSRC}/lib${ENAME}.a ${STAGEDIR}${PREFIX}/lib
+	${INSTALL_LIB} ${WRKSRC}/lib${ENAME}.so ${STAGEDIR}${PREFIX}/lib
+
+.include <bsd.port.mk>
diff --git a/math/tiny-bignum-c/distinfo b/math/tiny-bignum-c/distinfo
new file mode 100644
index 000000000000..1553cba184fc
--- /dev/null
+++ b/math/tiny-bignum-c/distinfo
@@ -0,0 +1,3 @@
+TIMESTAMP = 1632474320
+SHA256 (kokke-tiny-bignum-c-g20210222-201fb20_GH0.tar.gz) = 20838d8c239994de91394724c43c1e7f1207821c59974228976e10e39ee7002b
+SIZE (kokke-tiny-bignum-c-g20210222-201fb20_GH0.tar.gz) = 34401
diff --git a/math/tiny-bignum-c/files/patch-Makefile b/math/tiny-bignum-c/files/patch-Makefile
new file mode 100644
index 000000000000..db5359aa1a19
--- /dev/null
+++ b/math/tiny-bignum-c/files/patch-Makefile
@@ -0,0 +1,8 @@
+--- Makefile.orig	2021-02-22 22:03:20 UTC
++++ Makefile
+@@ -1,4 +1,4 @@
+-CC     := gcc
++#CC     := gcc
+ MACROS := 
+ CFLAGS := -I. -Wundef -Wall -Wextra -O3 $(MACROS)
+ 
diff --git a/math/tiny-bignum-c/pkg-descr b/math/tiny-bignum-c/pkg-descr
new file mode 100644
index 000000000000..816f5726db29
--- /dev/null
+++ b/math/tiny-bignum-c/pkg-descr
@@ -0,0 +1,7 @@
+tiny-bignum-c is a small portable arbitrary-precision unsigned integer
+arithmetic in C, for calculating with large numbers.
+
+Uses an array of uint8_t, uint16_t or uint32_t as underlying data-type utilizing
+all bits in each word.
+
+WWW: https://github.com/kokke/tiny-bignum-c