diff --git a/lib/ww/lex/lex.ww b/lib/ww/lex/lex.ww
index f9564c5d..e5c85d41 100644
--- a/lib/ww/lex/lex.ww
+++ b/lib/ww/lex/lex.ww
@@ -18,6 +18,7 @@ package lex;
 import os;
 import ascii;
 import strings;
+import strconv;
 
 // isidstart / isidpart — identifier classification. Lexer-local
 // because the "alpha or '_' / alnum or '_'" set isn't part of Hare's
@@ -99,32 +100,15 @@ fn curpos(l: *lex, out: *pos) void = {
 	out.col = l.col;
 };
 
-// putuint — write `v` (signed, but always non-negative here) to fd 2
-// in decimal. Standalone so errat doesn't drag in fmt and create a
-// dependency cycle with strconv.
-fn putuint(fd: i32, v: i32) void = {
-	let tmp: [16]u8;
-	let i: i32 = 0;
-	let n: i32 = v;
-	for (n > 0) {
-		tmp[i] = ((n % 10) + 48): u8;
-		n = n / 10;
-		i += 1;
-	};
-	if (i == 0) { tmp[0] = 48u8; i = 1; };
-	let buf: [16]u8;
-	let m: i32 = 0;
-	for (i > 0) { i -= 1; buf[m] = tmp[i]; m += 1; };
-	os.write(fd, buf.ptr, m: u64);
-};
-
 fn errat(l: *lex, p: *pos, msg: str) void = {
 	let pf: str = p.file;
 	os.write(2, pf.ptr, pf.len: u64);
 	os.write(2, ":".ptr, 1u64);
-	putuint(2, p.line);
+	let ls: str = strconv.u64tos(p.line: u64, strconv.base.DEC);
+	os.write(2, ls.ptr, ls.len: u64);
 	os.write(2, ":".ptr, 1u64);
-	putuint(2, p.col);
+	let cs: str = strconv.u64tos(p.col: u64, strconv.base.DEC);
+	os.write(2, cs.ptr, cs.len: u64);
 	os.write(2, ": error: ".ptr, 9u64);
 	os.write(2, msg.ptr, msg.len: u64);
 	os.write(2, "\n".ptr, 1u64);
diff --git a/selfhost/cmd/w6c/main.combined.ww b/selfhost/cmd/w6c/main.combined.ww
index ea030102..aa037f42 100644
--- a/selfhost/cmd/w6c/main.combined.ww
+++ b/selfhost/cmd/w6c/main.combined.ww
@@ -6790,6 +6790,7 @@ package lex;
 import os;
 import ascii;
 import strings;
+import strconv;
 
 // isidstart / isidpart — identifier classification. Lexer-local
 // because the "alpha or '_' / alnum or '_'" set isn't part of Hare's
@@ -6871,32 +6872,15 @@ fn curpos(l: *lex, out: *pos) void = {
 	out.col = l.col;
 };
 
-// putuint — write `v` (signed, but always non-negative here) to fd 2
-// in decimal. Standalone so errat doesn't drag in fmt and create a
-// dependency cycle with strconv.
-fn putuint(fd: i32, v: i32) void = {
-	let tmp: [16]u8;
-	let i: i32 = 0;
-	let n: i32 = v;
-	for (n > 0) {
-		tmp[i] = ((n % 10) + 48): u8;
-		n = n / 10;
-		i += 1;
-	};
-	if (i == 0) { tmp[0] = 48u8; i = 1; };
-	let buf: [16]u8;
-	let m: i32 = 0;
-	for (i > 0) { i -= 1; buf[m] = tmp[i]; m += 1; };
-	os.write(fd, buf.ptr, m: u64);
-};
-
 fn errat(l: *lex, p: *pos, msg: str) void = {
 	let pf: str = p.file;
 	os.write(2, pf.ptr, pf.len: u64);
 	os.write(2, ":".ptr, 1u64);
-	putuint(2, p.line);
+	let ls: str = strconv.u64tos(p.line: u64, strconv.base.DEC);
+	os.write(2, ls.ptr, ls.len: u64);
 	os.write(2, ":".ptr, 1u64);
-	putuint(2, p.col);
+	let cs: str = strconv.u64tos(p.col: u64, strconv.base.DEC);
+	os.write(2, cs.ptr, cs.len: u64);
 	os.write(2, ": error: ".ptr, 9u64);
 	os.write(2, msg.ptr, msg.len: u64);
 	os.write(2, "\n".ptr, 1u64);
diff --git a/selfhost/cmd/wwdump/main.combined.ww b/selfhost/cmd/wwdump/main.combined.ww
index 44673903..d681b893 100644
--- a/selfhost/cmd/wwdump/main.combined.ww
+++ b/selfhost/cmd/wwdump/main.combined.ww
@@ -6790,6 +6790,7 @@ package lex;
 import os;
 import ascii;
 import strings;
+import strconv;
 
 // isidstart / isidpart — identifier classification. Lexer-local
 // because the "alpha or '_' / alnum or '_'" set isn't part of Hare's
@@ -6871,32 +6872,15 @@ fn curpos(l: *lex, out: *pos) void = {
 	out.col = l.col;
 };
 
-// putuint — write `v` (signed, but always non-negative here) to fd 2
-// in decimal. Standalone so errat doesn't drag in fmt and create a
-// dependency cycle with strconv.
-fn putuint(fd: i32, v: i32) void = {
-	let tmp: [16]u8;
-	let i: i32 = 0;
-	let n: i32 = v;
-	for (n > 0) {
-		tmp[i] = ((n % 10) + 48): u8;
-		n = n / 10;
-		i += 1;
-	};
-	if (i == 0) { tmp[0] = 48u8; i = 1; };
-	let buf: [16]u8;
-	let m: i32 = 0;
-	for (i > 0) { i -= 1; buf[m] = tmp[i]; m += 1; };
-	os.write(fd, buf.ptr, m: u64);
-};
-
 fn errat(l: *lex, p: *pos, msg: str) void = {
 	let pf: str = p.file;
 	os.write(2, pf.ptr, pf.len: u64);
 	os.write(2, ":".ptr, 1u64);
-	putuint(2, p.line);
+	let ls: str = strconv.u64tos(p.line: u64, strconv.base.DEC);
+	os.write(2, ls.ptr, ls.len: u64);
 	os.write(2, ":".ptr, 1u64);
-	putuint(2, p.col);
+	let cs: str = strconv.u64tos(p.col: u64, strconv.base.DEC);
+	os.write(2, cs.ptr, cs.len: u64);
 	os.write(2, ": error: ".ptr, 9u64);
 	os.write(2, msg.ptr, msg.len: u64);
 	os.write(2, "\n".ptr, 1u64);