diff --git a/tests/printf.test b/tests/printf.test
index ebf536f..ded169e 100644
--- a/tests/printf.test
+++ b/tests/printf.test
@@ -7,35 +7,42 @@
 
 #testing "name" "command" "result" "infile" "stdin"
 
-testing "" "printf TEXT" "TEXT" "" ""
-testing "printf escapes" "printf 'one\ntwo\n\v\t\r\f\e\b\athree'" \
-  "one\ntwo\n\v\t\r\f\e\b\athree" "" ""
-testing "printf %b escapes" "printf %b 'one\ntwo\n\v\t\r\f\e\b\athree'" \
-  "one\ntwo\n\v\t\r\f\e\b\athree" "" ""
-testing "printf null" "printf 'x\0y' | od -An -tx1" ' 78 00 79\n' "" ""
-testing "printf trailing slash" "printf 'abc\'" 'abc\' "" ""
-testing "printf octal" "printf ' \1\002\429\045x'" ' \001\002"9%x' "" ""
-testing "printf not octal" "printf '\9'" '\9' "" ""
-testing "printf hex" "printf 'A\x1b\x2B\x3Q\xa' | od -An -tx1" \
-  ' 41 1b 2b 03 51 0a\n' "" ""
-testing "" "printf '%x\\n' 0x2a" "2a\n" "" ""
+# Disable shell builtin
+PRINTF="$(which printf)"
 
-testing "" "printf %d 42" "42" "" ""
-testing "" "printf %d 0x2a" "42" "" ""
-testing "" "printf %d 052" "42" "" ""
+testing "printf text" "$PRINTF TEXT" "TEXT" "" ""
+testing "printf escapes" "$PRINTF 'one\ntwo\n\v\t\r\f\e\b\athree'" \
+  "one\ntwo\n\v\t\r\f\e\b\athree" "" ""
+testing "printf %b escapes" "$PRINTF %b 'one\ntwo\n\v\t\r\f\e\b\athree'" \
+  "one\ntwo\n\v\t\r\f\e\b\athree" "" ""
+testing "printf null" "$PRINTF 'x\0y' | od -An -tx1" ' 78 00 79\n' "" ""
+testing "printf trailing slash" "$PRINTF 'abc\'" 'abc\' "" ""
+testing "printf octal" "$PRINTF ' \1\002\429\045x'" ' \001\002"9%x' "" ""
+testing "printf not octal" "$PRINTF '\9'" '\9' "" ""
+testing "printf hex" "$PRINTF 'A\x1b\x2B\x3Q\xa' | od -An -tx1" \
+  ' 41 1b 2b 03 51 0a\n' "" ""
+testing "printf " "$PRINTF '%x\n' 0x2a" "2a\n" "" ""
+
+testing "printf %d 42" "$PRINTF %d 42" "42" "" ""
+testing "printf %d 0x2a" "$PRINTF %d 0x2a" "42" "" ""
+testing "printf %d 052" "$PRINTF %d 052" "42" "" ""
+
+testing "printf %s width precision" \
+  "$PRINTF '%3s,%.3s,%10s,%10.3s' abcde fghij klmno pqrst" \
+  "abcde,fgh,     klmno,       pqr" "" ""
 
 testing "printf '%5d%4d' 1 21 321 4321 54321" \
-  "printf '%5d%4d' 1 21 321 4321 54321" "    1  21  321432154321   0" "" ""
-testing "printf '%c %c' 78 79" "printf '%c %c' 78 79" "7 7" "" ""
-testing "printf '%d %d' 78 79" "printf '%d %d' 78 79" "78 79" "" ""
-testing "printf '%f %f' 78 79" "printf '%f %f' 78 79" \
+  "$PRINTF '%5d%4d' 1 21 321 4321 54321" "    1  21  321432154321   0" "" ""
+testing "printf '%c %c' 78 79" "$PRINTF '%c %c' 78 79" "7 7" "" ""
+testing "printf '%d %d' 78 79" "$PRINTF '%d %d' 78 79" "78 79" "" ""
+testing "printf '%f %f' 78 79" "$PRINTF '%f %f' 78 79" \
   "78.000000 79.000000" "" ""
-testing "printf 'f f' 78 79" "printf 'f f' 78 79" "f f" "" ""
-testing "printf '%i %i' 78 79" "printf '%i %i' 78 79" "78 79" "" ""
-testing "printf '%o %o' 78 79" "printf '%o %o' 78 79" "116 117" "" ""
-testing "printf '%u %u' 78 79" "printf '%u %u' 78 79" "78 79" "" ""
-testing "printf '%u %u' -1 -2" "printf '%u %u' -1 -2" \
+testing "printf 'f f' 78 79" "$PRINTF 'f f' 78 79" "f f" "" ""
+testing "printf '%i %i' 78 79" "$PRINTF '%i %i' 78 79" "78 79" "" ""
+testing "printf '%o %o' 78 79" "$PRINTF '%o %o' 78 79" "116 117" "" ""
+testing "printf '%u %u' 78 79" "$PRINTF '%u %u' 78 79" "78 79" "" ""
+testing "printf '%u %u' -1 -2" "$PRINTF '%u %u' -1 -2" \
   "18446744073709551615 18446744073709551614" "" ""
-testing "printf '%x %X' 78 79" "printf '%x %X' 78 79" "4e 4F" "" ""
-testing "printf '%g %G' 78 79" "printf '%g %G' 78 79" "78 79" "" ""
-testing "printf '%s %s' 78 79" "printf '%s %s' 78 79" "78 79" "" ""
+testing "printf '%x %X' 78 79" "$PRINTF '%x %X' 78 79" "4e 4F" "" ""
+testing "printf '%g %G' 78 79" "$PRINTF '%g %G' 78 79" "78 79" "" ""
+testing "printf '%s %s' 78 79" "$PRINTF '%s %s' 78 79" "78 79" "" ""