3 files changed, 21 insertions, 3 deletions
diff --git a/libc/misc/ctype/Makefile b/libc/misc/ctype/Makefile
index ee3bfd04e..c329c942c 100644
--- a/libc/misc/ctype/Makefile
+++ b/libc/misc/ctype/Makefile
@@ -27,7 +27,7 @@ include $(TOPDIR)Rules.mak
 MSRC=ctype.c
 MOBJ= isalnum.o isalpha.o isascii.o iscntrl.o isdigit.o isgraph.o \
 	islower.o isprint.o ispunct.o isspace.o isupper.o isxdigit.o \
-	isxlower.o isxupper.o toascii.o tolower.o toupper.o
+	isxlower.o isxupper.o toascii.o tolower.o toupper.o isblank.o
 
 ifeq ($(HAS_LOCALE),true)
 	MOBJ += ctype_C.o
diff --git a/libc/misc/ctype/ctype.c b/libc/misc/ctype/ctype.c
index 5dc35cc72..a077dbf3c 100644
--- a/libc/misc/ctype/ctype.c
+++ b/libc/misc/ctype/ctype.c
@@ -118,6 +118,15 @@ isspace( int c )
 }
 #endif
 
+#ifdef L_isblank
+#undef isblank
+int
+isblank( int c )
+{
+    return (c == ' ' || c == '\t');
+}
+#endif
+
 #ifdef L_isupper
 #undef isupper
 int
@@ -266,6 +275,15 @@ isspace( int c )
 }
 #endif
 
+#ifdef L_isblank
+#undef isblank
+int
+isblank( int c )
+{
+    return _UC_ISCTYPE(c, ISblank);
+}
+#endif
+
 #ifdef L_isupper
 #undef isupper
 int
diff --git a/libc/misc/ctype/ctype_C.c b/libc/misc/ctype/ctype_C.c
index 2aa2690b6..190140752 100644
--- a/libc/misc/ctype/ctype_C.c
+++ b/libc/misc/ctype/ctype_C.c
@@ -8,7 +8,7 @@ const unsigned char _uc_ctype_b_C[LOCALE_BUF_SIZE] = {
 	/* 0x06, 6, 06 */	IScntrl,
 	/* 0x07, 7, 07 */	IScntrl,
 	/* 0x08, 8, 010 */	IScntrl,
-	/* 0x09, 9, 011 */	IScntrl|ISspace,
+	/* 0x09, 9, 011 */	IScntrl|ISspace|ISblank,
 	/* 0x0a, 10, 012 */	IScntrl|ISspace,
 	/* 0x0b, 11, 013 */	IScntrl|ISspace,
 	/* 0x0c, 12, 014 */	IScntrl|ISspace,
@@ -31,7 +31,7 @@ const unsigned char _uc_ctype_b_C[LOCALE_BUF_SIZE] = {
 	/* 0x1d, 29, 035 */	IScntrl,
 	/* 0x1e, 30, 036 */	IScntrl,
 	/* 0x1f, 31, 037 */	IScntrl,
-	/* 0x20, 32, 040 */	ISprint|ISspace,
+	/* 0x20, 32, 040 */	ISprint|ISspace|ISblank,
 	/* 0x21, 33, 041 */	ISprint|ISpunct,
 	/* 0x22, 34, 042 */	ISprint|ISpunct,
 	/* 0x23, 35, 043 */	ISprint|ISpunct,