diff --git a/libc/time/strptime.c b/libc/time/strptime.c
index c42d3e2a..86200e4a 100644
--- a/libc/time/strptime.c
+++ b/libc/time/strptime.c
@@ -20,6 +20,7 @@
 #include <ctype.h>
 #include <limits.h>
 #include <stdbool.h>
+#include <stdint.h>
 #include <string.h>
 #include <time.h>
 
@@ -28,16 +29,15 @@
 #define strptime mystrptime
 #endif
 
-static const char* wdays[] = {"sunday", "monday", "tuesday", "wednesday",
-                              "thursday", "friday", "saturday", NULL};
-static const char* months[] = {"january", "february", "march", "april", "may",
-                               "june", "july", "august", "september", "october",
-                               "november", "december", NULL};
+static const char* wdays[] = {"Sunday", "Monday", "Tuesday", "Wednesday",
+                              "Thursday", "Friday", "Saturday", NULL};
+static const char* months[] = {"January", "February", "March", "April", "May",
+                               "June", "July", "August", "September", "October",
+                               "November", "December", NULL};
 
-// TODO: Maximum width.
-static const char* strptime_match(const char* str,
-                                  int* output,
-                                  const char* const* list)
+static const char* strptime_str(const char* str,
+                                int* output,
+                                const char* const* list)
 {
 	for ( int i = 0; list[i]; i++ )
 	{
@@ -50,21 +50,29 @@ static const char* strptime_match(const char* str,
 	return NULL;
 }
 
-// TODO: Maximum width.
-static const char* strptime_digits(const char* str,
-                                   int* output,
-                                   int minimum,
-                                   int maximum,
-                                   int offset)
+static const char* strptime_num(const char* str,
+                                int* output,
+                                int minimum,
+                                int maximum,
+                                size_t min_digits,
+                                size_t max_digits,
+                                int offset)
 {
-	if ( *str < '0'|| '9' < *str )
-		return NULL;
-	// TODO: More exact with number of digits.
 	int value = 0;
-	while ( '0' <= *str && *str <= '9' )
-		if ( __builtin_mul_overflow(value, 10, &value) ||
-		     __builtin_add_overflow(value, *str++ - '0', &value) )
+	size_t i = 0;
+	while ( i < max_digits )
+	{
+		if ( str[i] < '0'|| '9' < str[i] )
+		{
+			if ( min_digits <= i )
+				break;
 			return NULL;
+		}
+		if ( __builtin_mul_overflow(value, 10, &value) ||
+		     __builtin_add_overflow(value, str[i++] - '0', &value) )
+			return NULL;
+	}
+	str += i;
 	if ( value < minimum || maximum < value  )
 		return NULL;
 	if ( __builtin_add_overflow(value, offset, &value) )
@@ -78,6 +86,7 @@ char* strptime(const char* restrict str,
 {
 	bool pm = false;
 	bool need_mktime = false;
+	int year_high = -1, year_low = -1;
 	for ( size_t i = 0; format[i]; )
 	{
 		if ( isspace((unsigned char) format[i]) )
@@ -100,6 +109,7 @@ char* strptime(const char* restrict str,
 		i++;
 		if ( format[i] == '0' || format[i] == '+'  )
 			i++;
+		bool has_width = '0' <= format[i] && format[i] <= '9';
 		size_t width = 0;
 		while ( '0' <= format[i] && format[i] <= '9' )
 			width = width * 10 + (format[i++] - '0');
@@ -113,35 +123,40 @@ char* strptime(const char* restrict str,
 		switch ( format[i] )
 		{
 		case 'a':
-		case 'A': str = strptime_match(str, &tm->tm_wday, wdays); break;
+		case 'A': str = strptime_str(str, &tm->tm_wday, wdays); break;
 		case 'b':
 		case 'B':
 		case 'h':
-			str = strptime_match(str, &tm->tm_mon, months);
+			str = strptime_str(str, &tm->tm_mon, months);
 			need_mktime = true;
 			break;
-		// TODO: %c locale time and date
-		// TODO: %C century
+		case 'c': str = strptime(str, "%a %b %e %H:%M:%S %Y", tm); break;
+		case 'C': str = strptime_num(str, &year_high, 0, 99, 1, 2, 0); break;
 		case 'd':
 		case 'e':
-			str = strptime_digits(str, &tm->tm_mday, 1, 31, 0);
+			str = strptime_num(str, &tm->tm_mday, 1, 31, 1, 2, 0);
 			need_mktime = true;
 			break;
 		case 'D': str = strptime(str, "%m/%d/%y", tm); break;
-		case 'H': str = strptime_digits(str, &tm->tm_hour, 0, 23, 0); break;
+		case 'H': str = strptime_num(str, &tm->tm_hour, 0, 23, 1, 2, 0); break;
 		case 'I':
-			str = strptime_digits(str, &tm->tm_hour, 1, 12, 0);
+			str = strptime_num(str, &tm->tm_hour, 1, 12, 1, 2, 0);
 			if ( tm->tm_hour == 12 )
 				tm->tm_hour = 0;
 			break;
-		case 'j': str = strptime_digits(str, &tm->tm_yday, 1, 366, -1); break;
+		case 'j': str = strptime_num(str, &tm->tm_yday, 1, 366, 3, 3, -1); break;
 		case 'm':
-			str = strptime_digits(str, &tm->tm_mon, 1, 12, -1);
+			str = strptime_num(str, &tm->tm_mon, 1, 12, 1, 2, -1);
 			need_mktime = true;
 			break;
-		case 'M': str = strptime_digits(str, &tm->tm_min, 0, 59, 0); break;
-		// TODO: %n whitesapce
-		// TODO: %t whitespace
+		case 'M': str = strptime_num(str, &tm->tm_min, 0, 59, 1, 2, 0); break;
+		case 'n':
+		case 't':
+			if ( !isspace((unsigned char) *str) )
+				return NULL;
+			do str++;
+			while ( isspace((unsigned char) *str) );
+			break;
 		case 'p':
 			if ( !strncasecmp(str, "am", 2) )
 				str += 2, pm = false;
@@ -152,17 +167,22 @@ char* strptime(const char* restrict str,
 			break;
 		case 'r': str = strptime(str, "%I:%M:%S %p", tm); break;
 		case 'R': str = strptime(str, "%H:%M", tm); break;
-		case 'S': str = strptime_digits(str, &tm->tm_sec, 0, 60, 0); break;
+		case 'S': str = strptime_num(str, &tm->tm_sec, 0, 60, 1, 2, 0); break;
 		case 'T': str = strptime(str, "%H:%M:%S", tm); break;
 		// TODO: %U week number
-		case 'w': str = strptime_digits(str, &tm->tm_wday, 0, 6, 0); break;
+		case 'w': str = strptime_num(str, &tm->tm_wday, 0, 6, 1, 1, 0); break;
 		// TODO: %W week number
 		case 'x': str = strptime(str, "%m/%d/%Y", tm); break;
 		case 'X': str = strptime(str, "%H:%M:%S", tm); break;
-		// TODO: %y non-century year
+		case 'y': str = strptime_num(str, &year_low, 0, 99, 1, 2, 0); break;
 		case 'Y':
-			// TODO: Minimum yield width.
-			str = strptime_digits(str, &tm->tm_year, INT_MIN, INT_MAX, -1900);
+			// POSIX divergence: Avoid year 10k problem by allowing more than
+			// four characters by default.
+			if ( !has_width )
+				width = SIZE_MAX;
+			// TODO: Allow leading + and - per POSIX.
+			str = strptime_num(str, &tm->tm_year, INT_MIN, INT_MAX, 1, width,
+			                   -1900);
 			need_mktime = true;
 			break;
 		case 'z':
@@ -170,8 +190,8 @@ char* strptime(const char* restrict str,
 			if ( *str != '-' || *str != '+' )
 				return NULL;
 			int hours, minutes;
-			if ( !(str = strptime_digits(str, &hours, -12, 12, 0)) ||
-			     !(str = strptime_digits(str, &minutes, 0, 59, 0)) )
+			if ( !(str = strptime_num(str, &hours, -12, 12, 2, 2, 0)) ||
+			     !(str = strptime_num(str, &minutes, 0, 59, 2, 2, 0)) )
 				return NULL;
 			tm->tm_isdst = 0;
 			// TODO: What is done with this timezone information?
@@ -198,8 +218,22 @@ char* strptime(const char* restrict str,
 	{
 		if ( pm )
 			tm->tm_hour += 12;
+		if ( year_high != -1 || year_low != -1 )
+		{
+			if ( year_high == -1 )
+				year_high = year_low < 70 ? 20 : 19;
+			else if ( year_low == -1 )
+				year_low = 0;
+			tm->tm_year = year_high * 100 + year_low - 1900;
+			need_mktime = true;
+		}
 		if ( need_mktime )
-			mktime(tm);
+		{
+			struct tm copy = *tm;
+			mktime(&copy);
+			tm->tm_wday = copy.tm_wday;
+			tm->tm_yday = copy.tm_yday;
+		}
 	}
 	return (char*) str;
 }