diff --git a/lib/c.zig b/lib/c.zig
index d59ef950f4..40b7008740 100644
--- a/lib/c.zig
+++ b/lib/c.zig
@@ -15,6 +15,7 @@ else
 
 comptime {
     _ = @import("c/inttypes.zig");
+    _ = @import("c/ctype.zig");
     _ = @import("c/stdlib.zig");
     _ = @import("c/math.zig");
 
diff --git a/lib/c/ctype.zig b/lib/c/ctype.zig
new file mode 100644
index 0000000000..3ebdcfa634
--- /dev/null
+++ b/lib/c/ctype.zig
@@ -0,0 +1,192 @@
+const std = @import("std");
+const common = @import("common.zig");
+const builtin = @import("builtin");
+
+comptime {
+    if (builtin.target.isMuslLibC() or builtin.target.isWasiLibC()) {
+        // Functions specific to musl and wasi-libc.
+        @export(&isalnum, .{ .name = "isalnum", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&isalpha, .{ .name = "isalpha", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&isblank, .{ .name = "isblank", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&iscntrl, .{ .name = "iscntrl", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&isdigit, .{ .name = "isdigit", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&isgraph, .{ .name = "isgraph", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&islower, .{ .name = "islower", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&isprint, .{ .name = "isprint", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&ispunct, .{ .name = "ispunct", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&isspace, .{ .name = "isspace", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&isupper, .{ .name = "isupper", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&isxdigit, .{ .name = "isxdigit", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&tolower, .{ .name = "tolower", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&toupper, .{ .name = "toupper", .linkage = common.linkage, .visibility = common.visibility });
+
+        @export(&__isalnum_l, .{ .name = "__isalnum_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__isalpha_l, .{ .name = "__isalpha_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__isblank_l, .{ .name = "__isblank_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__iscntrl_l, .{ .name = "__iscntrl_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__isdigit_l, .{ .name = "__isdigit_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__isgraph_l, .{ .name = "__isgraph_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__islower_l, .{ .name = "__islower_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__isprint_l, .{ .name = "__isprint_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__ispunct_l, .{ .name = "__ispunct_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__isspace_l, .{ .name = "__isspace_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__isupper_l, .{ .name = "__isupper_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__isxdigit_l, .{ .name = "__isxdigit_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__tolower_l, .{ .name = "__tolower_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__toupper_l, .{ .name = "__toupper_l", .linkage = common.linkage, .visibility = common.visibility });
+
+        @export(&__isalnum_l, .{ .name = "isalnum_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__isalpha_l, .{ .name = "isalpha_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__isblank_l, .{ .name = "isblank_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__iscntrl_l, .{ .name = "iscntrl_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__isdigit_l, .{ .name = "isdigit_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__isgraph_l, .{ .name = "isgraph_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__islower_l, .{ .name = "islower_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__isprint_l, .{ .name = "isprint_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__ispunct_l, .{ .name = "ispunct_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__isspace_l, .{ .name = "isspace_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__isupper_l, .{ .name = "isupper_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__isxdigit_l, .{ .name = "isxdigit_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__tolower_l, .{ .name = "tolower_l", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&__toupper_l, .{ .name = "toupper_l", .linkage = common.linkage, .visibility = common.visibility });
+
+        @export(&isascii, .{ .name = "isascii", .linkage = common.linkage, .visibility = common.visibility });
+        @export(&toascii, .{ .name = "toascii", .linkage = common.linkage, .visibility = common.visibility });
+    }
+}
+
+// NOTE: If the input is not representable as an unsigned char or is not EOF the behaviour is undefined.
+
+fn isalnum(c: c_int) callconv(.c) c_int {
+    return @intFromBool(std.ascii.isAlphanumeric(@intCast(c)));
+}
+
+fn __isalnum_l(c: c_int, locale: *anyopaque) callconv(.c) c_int {
+    _ = locale;
+    return isalnum(c);
+}
+
+fn isalpha(c: c_int) callconv(.c) c_int {
+    return @intFromBool(std.ascii.isAlphabetic(@intCast(c)));
+}
+
+fn __isalpha_l(c: c_int, locale: *anyopaque) callconv(.c) c_int {
+    _ = locale;
+    return isalpha(c);
+}
+
+fn isblank(c: c_int) callconv(.c) c_int {
+    return @intFromBool(c == ' ' or c == '\t');
+}
+
+fn __isblank_l(c: c_int, locale: *anyopaque) callconv(.c) c_int {
+    _ = locale;
+    return isblank(c);
+}
+
+fn iscntrl(c: c_int) callconv(.c) c_int {
+    return @intFromBool(std.ascii.isControl(@intCast(c)));
+}
+
+fn __iscntrl_l(c: c_int, locale: *anyopaque) callconv(.c) c_int {
+    _ = locale;
+    return iscntrl(c);
+}
+
+fn isdigit(c: c_int) callconv(.c) c_int {
+    return @intFromBool(std.ascii.isDigit(@intCast(c)));
+}
+
+fn __isdigit_l(c: c_int, locale: *anyopaque) callconv(.c) c_int {
+    _ = locale;
+    return isdigit(c);
+}
+
+fn isgraph(c: c_int) callconv(.c) c_int {
+    return @intFromBool(std.ascii.isGraphical(@intCast(c)));
+}
+
+fn __isgraph_l(c: c_int, locale: *anyopaque) callconv(.c) c_int {
+    _ = locale;
+    return isgraph(c);
+}
+
+fn islower(c: c_int) callconv(.c) c_int {
+    return @intFromBool(std.ascii.isLower(@intCast(c)));
+}
+
+fn __islower_l(c: c_int, locale: *anyopaque) callconv(.c) c_int {
+    _ = locale;
+    return islower(c);
+}
+
+fn isprint(c: c_int) callconv(.c) c_int {
+    return @intFromBool(std.ascii.isPrint(@intCast(c)));
+}
+
+fn __isprint_l(c: c_int, locale: *anyopaque) callconv(.c) c_int {
+    _ = locale;
+    return isprint(c);
+}
+
+fn ispunct(c: c_int) callconv(.c) c_int {
+    return @intFromBool(std.ascii.isPunctuation(@intCast(c)));
+}
+
+fn __ispunct_l(c: c_int, locale: *anyopaque) callconv(.c) c_int {
+    _ = locale;
+    return ispunct(c);
+}
+
+fn isspace(c: c_int) callconv(.c) c_int {
+    return @intFromBool(std.ascii.isWhitespace(@intCast(c)));
+}
+
+fn __isspace_l(c: c_int, locale: *anyopaque) callconv(.c) c_int {
+    _ = locale;
+    return isspace(c);
+}
+
+fn isupper(c: c_int) callconv(.c) c_int {
+    return @intFromBool(std.ascii.isUpper(@intCast(c)));
+}
+
+fn __isupper_l(c: c_int, locale: *anyopaque) callconv(.c) c_int {
+    _ = locale;
+    return isupper(c);
+}
+
+fn isxdigit(c: c_int) callconv(.c) c_int {
+    return @intFromBool(std.ascii.isHex(@intCast(c)));
+}
+
+fn __isxdigit_l(c: c_int, locale: *anyopaque) callconv(.c) c_int {
+    _ = locale;
+    return isxdigit(c);
+}
+
+fn tolower(c: c_int) callconv(.c) c_int {
+    return std.ascii.toLower(@intCast(c));
+}
+
+fn __tolower_l(c: c_int, locale: *anyopaque) callconv(.c) c_int {
+    _ = locale;
+    return tolower(c);
+}
+
+fn toupper(c: c_int) callconv(.c) c_int {
+    return std.ascii.toUpper(@intCast(c));
+}
+
+fn __toupper_l(c: c_int, locale: *anyopaque) callconv(.c) c_int {
+    _ = locale;
+    return toupper(c);
+}
+
+fn isascii(c: c_int) callconv(.c) c_int {
+    return @intFromBool(std.ascii.isAscii(@intCast(c)));
+}
+
+fn toascii(c: c_int) callconv(.c) c_int {
+    return c & 0x7F;
+}
diff --git a/lib/libc/musl/src/ctype/isalnum.c b/lib/libc/musl/src/ctype/isalnum.c
deleted file mode 100644
index 8018a2bc7e..0000000000
--- a/lib/libc/musl/src/ctype/isalnum.c
+++ /dev/null
@@ -1,13 +0,0 @@
-#include <ctype.h>
-
-int isalnum(int c)
-{
-	return isalpha(c) || isdigit(c);
-}
-
-int __isalnum_l(int c, locale_t l)
-{
-	return isalnum(c);
-}
-
-weak_alias(__isalnum_l, isalnum_l);
diff --git a/lib/libc/musl/src/ctype/isalpha.c b/lib/libc/musl/src/ctype/isalpha.c
deleted file mode 100644
index a87a937598..0000000000
--- a/lib/libc/musl/src/ctype/isalpha.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <ctype.h>
-#undef isalpha
-
-int isalpha(int c)
-{
-	return ((unsigned)c|32)-'a' < 26;
-}
-
-int __isalpha_l(int c, locale_t l)
-{
-	return isalpha(c);
-}
-
-weak_alias(__isalpha_l, isalpha_l);
diff --git a/lib/libc/musl/src/ctype/isascii.c b/lib/libc/musl/src/ctype/isascii.c
deleted file mode 100644
index 54ad3bf028..0000000000
--- a/lib/libc/musl/src/ctype/isascii.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <ctype.h>
-#undef isascii
-
-int isascii(int c)
-{
-	return !(c&~0x7f);
-}
diff --git a/lib/libc/musl/src/ctype/isblank.c b/lib/libc/musl/src/ctype/isblank.c
deleted file mode 100644
index 716da23a56..0000000000
--- a/lib/libc/musl/src/ctype/isblank.c
+++ /dev/null
@@ -1,13 +0,0 @@
-#include <ctype.h>
-
-int isblank(int c)
-{
-	return (c == ' ' || c == '\t');
-}
-
-int __isblank_l(int c, locale_t l)
-{
-	return isblank(c);
-}
-
-weak_alias(__isblank_l, isblank_l);
diff --git a/lib/libc/musl/src/ctype/iscntrl.c b/lib/libc/musl/src/ctype/iscntrl.c
deleted file mode 100644
index f27837ea53..0000000000
--- a/lib/libc/musl/src/ctype/iscntrl.c
+++ /dev/null
@@ -1,13 +0,0 @@
-#include <ctype.h>
-
-int iscntrl(int c)
-{
-	return (unsigned)c < 0x20 || c == 0x7f;
-}
-
-int __iscntrl_l(int c, locale_t l)
-{
-	return iscntrl(c);
-}
-
-weak_alias(__iscntrl_l, iscntrl_l);
diff --git a/lib/libc/musl/src/ctype/isdigit.c b/lib/libc/musl/src/ctype/isdigit.c
deleted file mode 100644
index 16beddb4ca..0000000000
--- a/lib/libc/musl/src/ctype/isdigit.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <ctype.h>
-#undef isdigit
-
-int isdigit(int c)
-{
-	return (unsigned)c-'0' < 10;
-}
-
-int __isdigit_l(int c, locale_t l)
-{
-	return isdigit(c);
-}
-
-weak_alias(__isdigit_l, isdigit_l);
diff --git a/lib/libc/musl/src/ctype/isgraph.c b/lib/libc/musl/src/ctype/isgraph.c
deleted file mode 100644
index 292d1983ec..0000000000
--- a/lib/libc/musl/src/ctype/isgraph.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <ctype.h>
-#undef isgraph
-
-int isgraph(int c)
-{
-	return (unsigned)c-0x21 < 0x5e;
-}
-
-int __isgraph_l(int c, locale_t l)
-{
-	return isgraph(c);
-}
-
-weak_alias(__isgraph_l, isgraph_l);
diff --git a/lib/libc/musl/src/ctype/islower.c b/lib/libc/musl/src/ctype/islower.c
deleted file mode 100644
index c3fa74c4cb..0000000000
--- a/lib/libc/musl/src/ctype/islower.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <ctype.h>
-#undef islower
-
-int islower(int c)
-{
-	return (unsigned)c-'a' < 26;
-}
-
-int __islower_l(int c, locale_t l)
-{
-	return islower(c);
-}
-
-weak_alias(__islower_l, islower_l);
diff --git a/lib/libc/musl/src/ctype/isprint.c b/lib/libc/musl/src/ctype/isprint.c
deleted file mode 100644
index b950816bcb..0000000000
--- a/lib/libc/musl/src/ctype/isprint.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <ctype.h>
-#undef isprint
-
-int isprint(int c)
-{
-	return (unsigned)c-0x20 < 0x5f;
-}
-
-int __isprint_l(int c, locale_t l)
-{
-	return isprint(c);
-}
-
-weak_alias(__isprint_l, isprint_l);
diff --git a/lib/libc/musl/src/ctype/ispunct.c b/lib/libc/musl/src/ctype/ispunct.c
deleted file mode 100644
index a491d5dc4b..0000000000
--- a/lib/libc/musl/src/ctype/ispunct.c
+++ /dev/null
@@ -1,13 +0,0 @@
-#include <ctype.h>
-
-int ispunct(int c)
-{
-	return isgraph(c) && !isalnum(c);
-}
-
-int __ispunct_l(int c, locale_t l)
-{
-	return ispunct(c);
-}
-
-weak_alias(__ispunct_l, ispunct_l);
diff --git a/lib/libc/musl/src/ctype/isspace.c b/lib/libc/musl/src/ctype/isspace.c
deleted file mode 100644
index 428813e798..0000000000
--- a/lib/libc/musl/src/ctype/isspace.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <ctype.h>
-#undef isspace
-
-int isspace(int c)
-{
-	return c == ' ' || (unsigned)c-'\t' < 5;
-}
-
-int __isspace_l(int c, locale_t l)
-{
-	return isspace(c);
-}
-
-weak_alias(__isspace_l, isspace_l);
diff --git a/lib/libc/musl/src/ctype/isupper.c b/lib/libc/musl/src/ctype/isupper.c
deleted file mode 100644
index bfd15acdbe..0000000000
--- a/lib/libc/musl/src/ctype/isupper.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <ctype.h>
-#undef isupper
-
-int isupper(int c)
-{
-	return (unsigned)c-'A' < 26;
-}
-
-int __isupper_l(int c, locale_t l)
-{
-	return isupper(c);
-}
-
-weak_alias(__isupper_l, isupper_l);
diff --git a/lib/libc/musl/src/ctype/isxdigit.c b/lib/libc/musl/src/ctype/isxdigit.c
deleted file mode 100644
index aab1a745b6..0000000000
--- a/lib/libc/musl/src/ctype/isxdigit.c
+++ /dev/null
@@ -1,13 +0,0 @@
-#include <ctype.h>
-
-int isxdigit(int c)
-{
-	return isdigit(c) || ((unsigned)c|32)-'a' < 6;
-}
-
-int __isxdigit_l(int c, locale_t l)
-{
-	return isxdigit(c);
-}
-
-weak_alias(__isxdigit_l, isxdigit_l);
diff --git a/lib/libc/musl/src/ctype/toascii.c b/lib/libc/musl/src/ctype/toascii.c
deleted file mode 100644
index f0e48e8e91..0000000000
--- a/lib/libc/musl/src/ctype/toascii.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <ctype.h>
-
-/* nonsense function that should NEVER be used! */
-int toascii(int c)
-{
-	return c & 0x7f;
-}
diff --git a/lib/libc/musl/src/ctype/tolower.c b/lib/libc/musl/src/ctype/tolower.c
deleted file mode 100644
index f10132ec2b..0000000000
--- a/lib/libc/musl/src/ctype/tolower.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <ctype.h>
-
-int tolower(int c)
-{
-	if (isupper(c)) return c | 32;
-	return c;
-}
-
-int __tolower_l(int c, locale_t l)
-{
-	return tolower(c);
-}
-
-weak_alias(__tolower_l, tolower_l);
diff --git a/lib/libc/musl/src/ctype/toupper.c b/lib/libc/musl/src/ctype/toupper.c
deleted file mode 100644
index 4e74a55c60..0000000000
--- a/lib/libc/musl/src/ctype/toupper.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <ctype.h>
-
-int toupper(int c)
-{
-	if (islower(c)) return c & 0x5f;
-	return c;
-}
-
-int __toupper_l(int c, locale_t l)
-{
-	return toupper(c);
-}
-
-weak_alias(__toupper_l, toupper_l);
diff --git a/src/libs/musl.zig b/src/libs/musl.zig
index b12088aae3..d19372fe37 100644
--- a/src/libs/musl.zig
+++ b/src/libs/musl.zig
@@ -535,18 +535,6 @@ const src_files = [_][]const u8{
     "musl/src/ctype/__ctype_get_mb_cur_max.c",
     "musl/src/ctype/__ctype_tolower_loc.c",
     "musl/src/ctype/__ctype_toupper_loc.c",
-    "musl/src/ctype/isalnum.c",
-    "musl/src/ctype/isalpha.c",
-    "musl/src/ctype/isascii.c",
-    "musl/src/ctype/isblank.c",
-    "musl/src/ctype/iscntrl.c",
-    "musl/src/ctype/isdigit.c",
-    "musl/src/ctype/isgraph.c",
-    "musl/src/ctype/islower.c",
-    "musl/src/ctype/isprint.c",
-    "musl/src/ctype/ispunct.c",
-    "musl/src/ctype/isspace.c",
-    "musl/src/ctype/isupper.c",
     "musl/src/ctype/iswalnum.c",
     "musl/src/ctype/iswalpha.c",
     "musl/src/ctype/iswblank.c",
@@ -560,10 +548,6 @@ const src_files = [_][]const u8{
     "musl/src/ctype/iswspace.c",
     "musl/src/ctype/iswupper.c",
     "musl/src/ctype/iswxdigit.c",
-    "musl/src/ctype/isxdigit.c",
-    "musl/src/ctype/toascii.c",
-    "musl/src/ctype/tolower.c",
-    "musl/src/ctype/toupper.c",
     "musl/src/ctype/towctrans.c",
     "musl/src/ctype/wcswidth.c",
     "musl/src/ctype/wctrans.c",
diff --git a/src/libs/wasi_libc.zig b/src/libs/wasi_libc.zig
index cfcd2ed7a3..d4d3cb1d88 100644
--- a/src/libs/wasi_libc.zig
+++ b/src/libs/wasi_libc.zig
@@ -643,18 +643,6 @@ const libc_top_half_src_files = [_][]const u8{
     "musl/src/ctype/__ctype_get_mb_cur_max.c",
     "musl/src/ctype/__ctype_tolower_loc.c",
     "musl/src/ctype/__ctype_toupper_loc.c",
-    "musl/src/ctype/isalnum.c",
-    "musl/src/ctype/isalpha.c",
-    "musl/src/ctype/isascii.c",
-    "musl/src/ctype/isblank.c",
-    "musl/src/ctype/iscntrl.c",
-    "musl/src/ctype/isdigit.c",
-    "musl/src/ctype/isgraph.c",
-    "musl/src/ctype/islower.c",
-    "musl/src/ctype/isprint.c",
-    "musl/src/ctype/ispunct.c",
-    "musl/src/ctype/isspace.c",
-    "musl/src/ctype/isupper.c",
     "musl/src/ctype/iswalnum.c",
     "musl/src/ctype/iswalpha.c",
     "musl/src/ctype/iswblank.c",
@@ -668,10 +656,6 @@ const libc_top_half_src_files = [_][]const u8{
     "musl/src/ctype/iswspace.c",
     "musl/src/ctype/iswupper.c",
     "musl/src/ctype/iswxdigit.c",
-    "musl/src/ctype/isxdigit.c",
-    "musl/src/ctype/toascii.c",
-    "musl/src/ctype/tolower.c",
-    "musl/src/ctype/toupper.c",
     "musl/src/ctype/towctrans.c",
     "musl/src/ctype/wcswidth.c",
     "musl/src/ctype/wctrans.c",