diff --git a/Makefile b/Makefile
index 653fe72..359c2e6 100644
--- a/Makefile
+++ b/Makefile
@@ -102,10 +102,10 @@ streq: libio streq.o
 	$(CC) $(CFLAGS) -o bin/streq build/libio.o build/streq.o
 
 str.o: src/str.c
-	$(CC) $(CFLAGS) -o build/str.o src/str.c
+	$(CC) $(CFLAGS) -c -o build/str.o src/str.c
 
 str: libio str.o
-	$(CC) $(CFLAGS) -o bin/str lib/libio.o src/str.o
+	$(CC) $(CFLAGS) -o bin/str build/libio.o build/str.o
 
 sleep.o: libio sysexits src/sleep.c usefulmacros
 	$(CC) $(CFLAGS) -c -o build/sleep.o src/sleep.c
diff --git a/src/str.c b/src/str.c
index 9a26b39..e93c4d5 100644
--- a/src/str.c
+++ b/src/str.c
@@ -1,50 +1,60 @@
+#include <ctype.h>
 #include <stddef.h>
+#include <string.h> /* strcmp(3) */
 #include <sysexits.h>
-#include <unistd.h>
-#include "libstrnum.h"
+#include <unistd.h> /* write(2) */
+#include "libio.h" /* fdputs(3) */
+#include "usefulmacros.h"
 
-int *typenames[] = {
-	(int []){ 'f','l','o','a','t', ASCII_US, STRIS_TYPE_FLOAT, '\0' },
-	(int []){ 'i','n','t', ASCII_US, STRIS_TYPE_INT, '\0' },
-	(int []){ 'u','i','n','t', ASCII_US, STRIS_TYPE_UINT, '\0' }
+static char *program_name = "str";
+
+static struct {
+	char *name;
+	int (*f)(int);
+}ctypes[] = {
+	{ "isalnum", isalnum },
+	{ "isalpha", isalpha },
+	{ "isblank", isblank },
+	{ "iscntrl", iscntrl },
+	{ "isdigit", isdigit },
+	{ "isxdigit", isxdigit },
+	{ "isgraph", isgraph },
+	{ "islower", islower },
+	{ "isprint", isprint },
+	{ "ispunct", ispunct },
+	{ "isspace", isspace },
+	{ "isupper", isupper }
 };
 
-size_t typenames_s = 3;
-
 int main(int argc, char *argv[]){
 	int i;
 	int j;
-	int k;
-	enum Strtype t;
 
-	for(k = 0; argv[0][k] != '\0'; ++k);
 	if(argc < 3){
-		write(2, "Usage: ", 7);
-		write(2, argv[0], k);
+error:		write(2, "Usage: ", 7);
+		fdputs(2, argv[0] == NULL ? program_name : argv[0]);
 		write(2, " [type] [string...]\n", 20);
 		return EX_USAGE;
 	}
 
-	j = 0;
-	t = 0;
-	for(i = 0; argv[1][i] != '\0'; ++i)
-		if(typenames[j][i] != argv[1][i])
-			if(++j >= typenames_s){
-				write(2, argv[0], k);
-				write(2, ": ", 2);
-				for(k = 0; argv[1][k] != '\0'; ++k);
-				write(2, argv[1], k);
-				write(2, ": No such type\n", 15);
-				return EX_DATAERR;
-			}
+	/* We could skip checking the first two characters and replace it with
+	 * a single if(argv[1][0] == 'i' && argv[1][1] == 's') or something
+	 * but it's simpler to just waste the cycles. */
 
+	/* slow but for our purposes this is fine */
+	for(i = 0; i < ARRAYLEN(ctypes); ++i)
+		if(strcmp(argv[1], ctypes[i].name) == 0){
+			i *= -1;
+			break;
+		}
+	if(i > 0)
+		goto error;
+	i *= -1;
 
-	if(argv[1][i] == '\0' && typenames[j][i] == ASCII_US)
-		t = typenames[j][i+1];
-
-	for(i = 2; i < argc; ++i)
-		if(!stris(t, argv[i]))
-			return 1;
+	for(argv += 2; *argv != NULL; ++argv)
+		for(j = 0; argv[0][j] != '\0'; ++j)
+			if(!ctypes[i].f(argv[0][j]))
+				return 1;
 
 	return 0;
 }