diff --git a/sqlite3/libc/build.sh b/sqlite3/libc/build.sh
index cff8387..b9082d7 100755
--- a/sqlite3/libc/build.sh
+++ b/sqlite3/libc/build.sh
@@ -10,10 +10,13 @@ SRCS="${1:-libc.c}"
 "../tools.sh"
 
 trap 'rm -f libc.c libc.tmp' EXIT
-echo '#include <string.h>' > libc.c
-echo '#include <stdlib.h>' >> libc.c
+cat << EOF > libc.c
+#include <string.h>
+#include <stdlib.h>
+EOF
 
 "$WASI_SDK/clang" --target=wasm32-wasi -std=c23 -g0 -O2 \
+	-Wall -Wextra -Wno-unused-parameter -Wno-unused-function \
 	-o libc.wasm -I. "$SRCS" \
 	-mexec-model=reactor \
 	-msimd128 -mmutable-globals -mmultivalue \
diff --git a/sqlite3/libc/libc.wasm b/sqlite3/libc/libc.wasm
index 4358642..0566afe 100755
Binary files a/sqlite3/libc/libc.wasm and b/sqlite3/libc/libc.wasm differ
diff --git a/sqlite3/libc/libc.wat b/sqlite3/libc/libc.wat
index 9944612..2b7a27d 100644
--- a/sqlite3/libc/libc.wat
+++ b/sqlite3/libc/libc.wat
@@ -142,42 +142,53 @@
   (local $3 i32)
   (local $4 i32)
   (local $5 i32)
-  (local $6 v128)
+  (local $6 i32)
   (local $7 v128)
-  (local.set $4
-   (i32.and
-    (local.get $0)
-    (i32.const 15)
+  (local $8 v128)
+  (local $scratch i32)
+  (block $block
+   (br_if $block
+    (i32.eqz
+     (local.get $2)
+    )
    )
-  )
-  (block $block1
-   (block $block
-    (if
-     (v128.any_true
-      (local.tee $6
-       (i8x16.eq
-        (v128.load
-         (local.tee $3
-          (i32.and
-           (local.get $0)
-           (i32.const -16)
-          )
-         )
-        )
+   (local.set $4
+    (i32.and
+     (local.get $0)
+     (i32.const 15)
+    )
+   )
+   (block $block2
+    (block $block1
+     (br_if $block1
+      (i32.eqz
+       (v128.any_true
         (local.tee $7
-         (i8x16.splat
-          (local.get $1)
+         (i8x16.eq
+          (v128.load
+           (local.tee $3
+            (i32.and
+             (local.get $0)
+             (i32.const -16)
+            )
+           )
+          )
+          (local.tee $8
+           (i8x16.splat
+            (local.get $1)
+           )
+          )
          )
         )
        )
       )
      )
-     (then
-      (br_if $block
-       (local.tee $1
+     (br_if $block1
+      (i32.eqz
+       (local.tee $5
         (i32.and
          (i8x16.bitmask
-          (local.get $6)
+          (local.get $7)
          )
          (i32.shl
           (i32.const -1)
@@ -187,44 +198,63 @@
        )
       )
      )
+     (local.set $1
+      (local.get $2)
+     )
+     (br $block2)
     )
-    (br_if $block1
-     (i32.gt_u
+    (br_if $block
+     (i32.lt_u
+      (local.get $2)
       (local.tee $1
        (i32.sub
-        (i32.add
-         (local.get $2)
-         (local.get $4)
+        (local.get $2)
+        (local.tee $3
+         (i32.sub
+          (i32.const 16)
+          (local.get $4)
+         )
         )
-        (i32.const 16)
        )
       )
-      (local.get $2)
+     )
+    )
+    (br_if $block
+     (i32.eqz
+      (local.get $1)
      )
     )
     (local.set $3
      (i32.add
-      (i32.sub
-       (local.get $0)
-       (local.get $4)
-      )
-      (i32.const 16)
+      (local.get $0)
+      (local.get $3)
      )
     )
-    (block $block2
+    (block $block3
      (loop $label
-      (br_if $block2
+      (br_if $block3
        (v128.any_true
-        (local.tee $6
+        (local.tee $7
          (i8x16.eq
           (v128.load
            (local.get $3)
           )
-          (local.get $7)
+          (local.get $8)
          )
         )
        )
       )
+      (br_if $block
+       (i32.gt_u
+        (local.tee $0
+         (i32.sub
+          (local.get $1)
+          (i32.const 16)
+         )
+        )
+        (local.get $1)
+       )
+      )
       (local.set $3
        (i32.add
         (local.get $3)
@@ -232,35 +262,49 @@
        )
       )
       (br_if $label
-       (i32.ge_u
-        (local.get $1)
-        (local.tee $1
-         (i32.sub
-          (local.get $1)
-          (i32.const 16)
+       (i32.eqz
+        (block (result i32)
+         (local.set $scratch
+          (i32.eq
+           (local.get $1)
+           (i32.const 16)
+          )
          )
+         (local.set $1
+          (local.get $0)
+         )
+         (local.get $scratch)
         )
        )
       )
      )
-     (br $block1)
+     (br $block)
     )
-    (local.set $1
+    (local.set $5
      (i8x16.bitmask
-      (local.get $6)
+      (local.get $7)
      )
     )
    )
-   (local.set $5
-    (i32.add
-     (local.get $3)
-     (i32.ctz
+   (local.set $6
+    (select
+     (i32.add
+      (local.get $3)
+      (local.tee $0
+       (i32.ctz
+        (local.get $5)
+       )
+      )
+     )
+     (i32.const 0)
+     (i32.lt_u
+      (local.get $0)
       (local.get $1)
      )
     )
    )
   )
-  (local.get $5)
+  (local.get $6)
  )
  (func $strlen (param $0 i32) (result i32)
   (local $1 i32)
diff --git a/sqlite3/libc/libc_test.go b/sqlite3/libc/libc_test.go
index 9fd4c3a..ba7bbca 100644
--- a/sqlite3/libc/libc_test.go
+++ b/sqlite3/libc/libc_test.go
@@ -116,6 +116,9 @@ func Benchmark_memchr(b *testing.B) {
 	if got := call(memchr, ptr1, 5, size); got != ptr1+size/2 {
 		b.Fatal(got)
 	}
+	if got := call(memchr, ptr1, 5, size/2); got != 0 {
+		b.Fatal(got, ptr1+size/2)
+	}
 }
 
 func Benchmark_memcmp(b *testing.B) {
diff --git a/sqlite3/libc/string.h b/sqlite3/libc/string.h
index ea4d5bb..140d701 100644
--- a/sqlite3/libc/string.h
+++ b/sqlite3/libc/string.h
@@ -45,7 +45,7 @@ void *memmove(void *dest, const void *src, size_t n) {
 // aligned address less than memory size.
 //
 // These also assume unaligned access is not painfully slow,
-// but that bitmask extraction is slow on AArch64.
+// but that bitmask extraction is really slow on AArch64.
 
 __attribute__((weak))
 int memcmp(const void *v1, const void *v2, size_t n) {
@@ -75,13 +75,14 @@ void *memchr(const void *v, int c, size_t n) {
   const v128_t *w = (void *)(v - align);
   const v128_t wc = wasm_i8x16_splat(c);
 
-  while (true) {
+  while (n) {
     const v128_t cmp = wasm_i8x16_eq(*w, wc);
     if (wasm_v128_any_true(cmp)) {
       int mask = wasm_i8x16_bitmask(cmp) >> align << align;
       __builtin_assume(mask || align);
       if (mask) {
-        return (void *)w + __builtin_ctz(mask);
+        size_t ctz = __builtin_ctz(mask);
+        return ctz < n ? (void *)w + ctz : NULL;
       }
     }
     if (__builtin_sub_overflow(n, sizeof(v128_t) - align, &n)) {
@@ -90,6 +91,7 @@ void *memchr(const void *v, int c, size_t n) {
     align = 0;
     w++;
   }
+  return NULL;
 }
 
 __attribute__((weak))
@@ -111,12 +113,7 @@ size_t strlen(const char *s) {
   }
 }
 
-__attribute__((weak))
-int strcmp(const char *s1, const char *s2) {
-  if (__builtin_constant_p(__builtin_strlen(s2))) {
-    return strncmp(s1, s2, __builtin_strlen(s2));
-  }
-
+static int __strcmp(const char *s1, const char *s2) {
   const v128_t *const limit =
       (v128_t *)(__builtin_wasm_memory_size(0) * PAGESIZE) - 1;
 
@@ -144,6 +141,14 @@ int strcmp(const char *s1, const char *s2) {
   return 0;
 }
 
+__attribute__((weak, always_inline))
+int strcmp(const char *s1, const char *s2) {
+  if (__builtin_constant_p(strlen(s2))) {
+    return strncmp(s1, s2, strlen(s2));
+  }
+  return __strcmp(s1, s2);
+}
+
 __attribute__((weak))
 int strncmp(const char *s1, const char *s2, size_t n) {
   const v128_t *const limit =
@@ -173,12 +178,7 @@ int strncmp(const char *s1, const char *s2, size_t n) {
   return 0;
 }
 
-__attribute__((always_inline))
 static char *__strchrnul(const char *s, int c) {
-  if (__builtin_constant_p(c) && (char)c == 0) {
-    return (char *)s + strlen(s);
-  }
-
   uintptr_t align = (uintptr_t)s % sizeof(v128_t);
   const v128_t *w = (void *)(s - align);
   const v128_t wc = wasm_i8x16_splat(c);
@@ -197,13 +197,19 @@ static char *__strchrnul(const char *s, int c) {
   }
 }
 
-__attribute__((weak))
+__attribute__((weak, always_inline))
 char *strchrnul(const char *s, int c) {
+  if (__builtin_constant_p(c) && (char)c == 0) {
+    return (char *)s + strlen(s);
+  }
   return __strchrnul(s, c);
 }
 
-__attribute__((weak))
+__attribute__((weak, always_inline))
 char *strchr(const char *s, int c) {
+  if (__builtin_constant_p(c) && (char)c == 0) {
+    return (char *)s + strlen(s);
+  }
   char *r = __strchrnul(s, c);
   return *(char *)r == (char)c ? r : NULL;
 }