diff --git a/.gitignore b/.gitignore
index d6ead37..010a8eb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -36,4 +36,5 @@ test/ksort_test
 test/ksort_test-stl
 test/kstring_bench
 test/kstring_bench2
+test/kstring_test
 test/kvec_test
diff --git a/test/Makefile b/test/Makefile
index cc52bb9..22c7261 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -3,7 +3,7 @@ CXX=g++
 CFLAGS=-g -Wall -O2 -I..
 CXXFLAGS=$(CFLAGS)
 PROGS=kbtree_test khash_keith khash_keith2 khash_test klist_test kseq_test kseq_bench \
-		kseq_bench2 ksort_test ksort_test-stl kvec_test kmin_test kstring_bench kstring_bench2
+		kseq_bench2 ksort_test ksort_test-stl kvec_test kmin_test kstring_bench kstring_bench2 kstring_test
 
 all:$(PROGS)
 
@@ -52,3 +52,5 @@ kstring_bench:kstring_bench.c ../kstring.h ../kstring.c
 kstring_bench2:kstring_bench2.c ../kstring.h ../kstring.c
 		$(CC) $(CFLAGS) -o $@ kstring_bench2.c ../kstring.c
 
+kstring_test:kstring_test.c ../kstring.h ../kstring.c
+		$(CC) $(CFLAGS) -o $@ kstring_test.c ../kstring.c
diff --git a/test/kstring_test.c b/test/kstring_test.c
new file mode 100644
index 0000000..76f9532
--- /dev/null
+++ b/test/kstring_test.c
@@ -0,0 +1,76 @@
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "kstring.h"
+
+int nfail = 0;
+
+void check(const char *what, const kstring_t *ks, const char *correct)
+{
+	if (ks->l != strlen(correct) || strcmp(ks->s, correct) != 0) {
+		fprintf(stderr, "%s produced \"%.*s\" (\"%s\" is correct)\tFAIL\n", what, (int)(ks->l), ks->s, correct);
+		nfail++;
+	}
+}
+
+void test_kputw(kstring_t *ks, int n)
+{
+	char buf[16];
+
+	ks->l = 0;
+	kputw(n, ks);
+
+	sprintf(buf, "%d", n);
+	check("kputw()", ks, buf);
+}
+
+void test_kputl(kstring_t *ks, long n)
+{
+	char buf[24];
+
+	ks->l = 0;
+	kputl(n, ks);
+
+	sprintf(buf, "%ld", n);
+	check("kputl()", ks, buf);
+}
+
+int main()
+{
+	kstring_t ks;
+
+	ks.l = ks.m = 0;
+	ks.s = NULL;
+
+	test_kputw(&ks, 0);
+	test_kputw(&ks, 1);
+	test_kputw(&ks, 37);
+	test_kputw(&ks, 12345);
+	test_kputw(&ks, -12345);
+	test_kputw(&ks, INT_MAX);
+	test_kputw(&ks, -INT_MAX);
+	test_kputw(&ks, INT_MIN);
+
+	test_kputl(&ks, 0);
+	test_kputl(&ks, 1);
+	test_kputl(&ks, 37);
+	test_kputl(&ks, 12345);
+	test_kputl(&ks, -12345);
+	test_kputl(&ks, INT_MAX);
+	test_kputl(&ks, -INT_MAX);
+	test_kputl(&ks, INT_MIN);
+	test_kputl(&ks, LONG_MAX);
+	test_kputl(&ks, -LONG_MAX);
+	test_kputl(&ks, LONG_MIN);
+
+	free(ks.s);
+
+	if (nfail > 0) {
+		fprintf(stderr, "Total failures: %d\n", nfail);
+		return EXIT_FAILURE;
+	}
+
+	return EXIT_SUCCESS;
+}