diff --git a/src/string.c b/src/string.c
index 4b8378275..92a36ef33 100644
--- a/src/string.c
+++ b/src/string.c
@@ -101,7 +101,7 @@ string_expand(char *dst, size_t dstlen, const char *src, int srclen, int tabsize
 
 			if (expanded + size >= dstlen - 1)
 				expanded = dstlen - size - 1;
-			memcpy(dst + size, "        ", expanded);
+			memset(dst + size, ' ', expanded);
 			size += expanded;
 		} else if (isspace((unsigned char)c) || iscntrl((unsigned char)c)) {
 			dst[size++] = ' ';
diff --git a/test/tigrc/tab-size-test b/test/tigrc/tab-size-test
new file mode 100755
index 000000000..c519a2c46
--- /dev/null
+++ b/test/tigrc/tab-size-test
@@ -0,0 +1,47 @@
+#!/bin/sh
+
+. libtest.sh
+
+export LINES=8
+
+printf 'left\tright\n\tleading\none\t\ttwo\n12345678\tboundary\n' > stdin
+
+steps ':save-display tabs.screen'
+
+for tab_size in 8 9 16 32; do
+	tigrc <<EOF
+set tab-size = $tab_size
+EOF
+
+	test_tig
+	sed -n '1,4p' tabs.screen > "tabs-$tab_size"
+	assert_equals stderr < /dev/null
+done
+
+assert_equals tabs-8 strict <<EOF
+left    right
+        leading
+one             two
+12345678        boundary
+EOF
+
+assert_equals tabs-9 strict <<EOF
+left     right
+         leading
+one               two
+12345678 boundary
+EOF
+
+assert_equals tabs-16 strict <<EOF
+left            right
+                leading
+one                             two
+12345678        boundary
+EOF
+
+assert_equals tabs-32 strict <<EOF
+left                            right
+                                leading
+one                                                             two
+12345678                        boundary
+EOF