diff --git a/Makefile b/Makefile
index a870852..d71ad1c 100644
--- a/Makefile
+++ b/Makefile
@@ -1,12 +1,12 @@
 CFLAGS = -g -Wall -Wextra -Werror
 
-objects = main.o input.o trans.o
+objects = main.o input.o encode.o
 
 b64 : $(objects)
 	cc -o b64 $(objects)
 
-main.o trans.o input.o : input.h
-main.o trans.o : trans.h
+main.o input.o : input.h
+main.o encode.o : encode.h
 
 .PHONY : clean
 clean :
diff --git a/encode.c b/encode.c
new file mode 100644
index 0000000..cee611f
--- /dev/null
+++ b/encode.c
@@ -0,0 +1,100 @@
+#include "encode.h"
+
+#define PADDING '='
+
+unsigned char b64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
+                      "abcdefghijklmnopqrstuvwxyz" \
+                      "0123456789" \
+                      "+/";
+
+unsigned char b64u[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
+                       "abcdefghijklmnopqrstuvwxyz" \
+                       "0123456789" \
+                       "-_";
+
+int
+encode(unsigned char *op, int olen, unsigned char *sp, int url)
+{
+    int n;
+    unsigned char *sb, *enc;
+
+    sb = sp;
+    enc = (!url) ? b64 : b64u;
+    switch (olen) {
+        case 3:
+            *sp++ = enc[(*op & ~3) >> 2];
+            n = (*op++ & 3) << 4;
+            *sp++ = enc[n + ((*op & ~15) >> 4)];
+            n = (*op++ & 15) << 2;
+            *sp++ = enc[n + ((*op & 192) >> 6)];
+            *sp = enc[*op & ~192];
+            break;
+        case 2:
+            *sp++ = enc[(*op & ~3) >> 2];
+            n = (*op++ & 3) << 4;
+            *sp++ = enc[n + ((*op & ~15) >> 4)];
+            *sp++ = enc[(*op & 15) << 2];
+            *sp = PADDING;
+            break;
+        case 1:
+            *sp++ = enc[(*op & ~3) >> 2];
+            *sp++ = enc[(*op & 3) << 4];
+            *sp++ = PADDING;
+            *sp = PADDING;
+            break;
+    }
+
+    return sp-sb+1;
+}
+
+int
+decode(unsigned char *sp, int slen, unsigned char *op, int url)
+{
+    int n, b, atob(int c, int url);
+    unsigned char *ob;
+
+    ob = op;
+    switch (slen) {
+        case 4:
+            n = atob(*sp++, url) << 2;
+            b = atob(*sp++, url);
+            *op++ = n + ((b & ~15) >> 4);
+
+            n = (b & 15) << 4;
+            b = atob(*sp++, url);
+            *op++ = n + ((b & ~3) >> 2);
+
+            *op = ((b & 3) << 6) + atob(*sp, url);
+            break;
+        case 3:
+            n = atob(*sp++, url) << 2;
+            b = atob(*sp++, url);
+            *op++ = n + ((b & ~15) >> 4);
+
+            n = (b & 15) << 4;
+            *op = n + ((atob(*sp, url) & ~3) >> 2);
+            break;
+        case 2:
+            n = atob(*sp++, url) << 2;
+            *op = n + ((atob(*sp, url) & ~15) >> 4);
+            break;
+    }
+
+    return op-ob+1;
+}
+
+int atob(int c, int url)
+{
+    if (c >= 'A' && c <= 'Z')
+        c -= 'A';
+    else if (c >= 'a' && c <= 'z')
+        c = c - 'a' + 26;
+    else if (c >= '0' && c <= '9')
+        c = c - '0' + 26 * 2;
+    else if (c == ((!url) ? '+' : '-'))
+        c = 62;
+    else
+        c = 63;
+
+    return c;
+}
diff --git a/encode.h b/encode.h
new file mode 100644
index 0000000..2ea285a
--- /dev/null
+++ b/encode.h
@@ -0,0 +1,10 @@
+#ifndef HEADER_ENCODE
+#define HEADER_ENCODE
+
+int
+encode(unsigned char *op, int olen, unsigned char *sp, int url);
+
+int
+decode(unsigned char *sp, int slen, unsigned char *op, int url);
+
+#endif
diff --git a/input.c b/input.c
index 855445a..cfe80b1 100644
--- a/input.c
+++ b/input.c
@@ -1,37 +1,30 @@
 #include "input.h"
 
-#define OBUFSIZE  4
-#define SBUFSIZE  5
-
 #define PADDING '='
 
-unsigned char o[OBUFSIZE];
-unsigned char s[SBUFSIZE];
-
-unsigned char *
-getocts(FILE *fp, int *np)
+int
+getocts(FILE *fp, unsigned char *o, int olen)
 {
-    int n, c;
+    int c, n;
 
     n = 0;
-    while (n < OBUFSIZE-1 && (c = fgetc(fp)) != EOF)
+    while (n < olen-1 && (c = fgetc(fp)) != EOF)
         o[n++] = c;
-    *np = n;
 
-    return (*np) ? o : NULL;
+    return n;
 }
 
-unsigned char *
-getsxts(FILE *fp, int *np)
+int
+getsxts(FILE *fp, unsigned char *s, int slen)
 {
-    int n, p, c;
+    int c, n, pad;
 
-    n = p = 0;
-    while (n < SBUFSIZE-1 && (c = fgetc(fp)) != EOF && c != PADDING)
-        s[n++] = c;
-    while (n+p < SBUFSIZE-1)
-        s[n+p++] = PADDING;
-    *np = n;
+    n = pad = 0;
+    while (n < slen-1 && (c = fgetc(fp)) != EOF && c != PADDING)
+        if (c != '\n')
+            s[n++] = c;
+    while (n+pad < slen-1)
+        s[n+pad++] = PADDING;
 
-    return (n) ? s : NULL;
+    return n;
 }
diff --git a/input.h b/input.h
index 178f17b..42bd4a6 100644
--- a/input.h
+++ b/input.h
@@ -3,13 +3,10 @@
 
 #include <stdio.h>
 
-extern unsigned char o[];
-extern unsigned char s[];
+int
+getocts(FILE *fp, unsigned char *o, int olen);
 
-unsigned char *
-getocts(FILE *fp, int *np);
-
-unsigned char *
-getsxts(FILE *fp, int *np);
+int
+getsxts(FILE *fp, unsigned char *s, int slen);
 
 #endif
diff --git a/main.c b/main.c
index b657c99..9cb544c 100644
--- a/main.c
+++ b/main.c
@@ -1,23 +1,31 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include "input.h"
-#include "trans.h"
+#include "encode.h"
+
+#define OBUFSIZE 4
+#define SBUFSIZE 5
+
+unsigned char obuf[OBUFSIZE];
+unsigned char sbuf[SBUFSIZE];
 
 int
 main(int argc, char *argv[])
 {
-    int c, n, dec, hlp;
+    int c, n, dec, url, hlp;
     char *prog = *argv;
-    unsigned char *b;
-    FILE *fp;
+    FILE *in, *out;
 
-    dec = hlp = 0;
+    dec = url = hlp = 0;
     while (--argc > 0 && (*++argv)[0] == '-')
         while ((c = *++argv[0]))
             switch (c) {
                 case 'd':
                     dec = 1;
                     break;
+                case 'u':
+                    url = 1;
+                    break;
                 case 'h':
                     hlp = 1;
                     break;
@@ -27,32 +35,32 @@ main(int argc, char *argv[])
                     break;
             }
     if (hlp) {
-        fprintf(stdout, "Usage: %s -d -h file\n", prog);
-    } else if (argc != 1) {
-        if (dec) {
-            while ((b = getsxts(stdin, &n))) {
-                    b = decode(b, &n);
-                    fwrite(b, sizeof(*b), n, stdout);
-            }
-        } else {
-            while ((b = getocts(stdin, &n)))
-                    printf("%s", encode(b, n));
-        }
+        fprintf(stdout, "Usage: %s -d -h infile outfile\n", prog);
     } else {
-        if ((fp = fopen(*argv, "r")) == NULL) {
+        if (argc >= 1 && (in = fopen(*argv, "r")) == NULL) {
             fprintf(stderr, "%s: can't open %s\n", prog, *argv);
             exit(EXIT_FAILURE);
         }
-        else if (dec) {
-            while ((b = getsxts(fp, &n))) {
-                    b = decode(b, &n);
-                    fwrite(b, sizeof(*b), n, stdout);
+        if (argc == 2 && (out = fopen(*(argv+1), "w")) == NULL) {
+            fprintf(stderr, "%s: can't open %s\n", prog, *(argv+1));
+            exit(EXIT_FAILURE);
+        }
+        if (dec) {
+            while ((n = getsxts((argc >= 1) ? in : stdin, sbuf, SBUFSIZE))) {
+                n = decode(sbuf, n, obuf, url);
+                fwrite(obuf, sizeof(*obuf), n, (argc == 2) ? out : stdout);
             }
         } else {
-            while ((b = getocts(fp, &n)))
-                    printf("%s", encode(b, n));
+            while ((n = getocts((argc >= 1) ? in : stdin, obuf, OBUFSIZE))) {
+                encode(obuf, n, sbuf, url);
+                fprintf((argc == 2) ? out : stdout, "%s", sbuf);
+            }
+            fprintf((argc == 2) ? out : stdout, "\n");
         }
-        fclose(fp);
+        if (in)
+            fclose(in);
+        if (out)
+            fclose(out);
     }
     exit(EXIT_SUCCESS);
 }
diff --git a/trans.c b/trans.c
deleted file mode 100644
index c29c576..0000000
--- a/trans.c
+++ /dev/null
@@ -1,97 +0,0 @@
-#include "trans.h"
-
-#define PADDING '='
-
-unsigned char b64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
-                      "abcdefghijklmnopqrstuvwxyz" \
-                      "0123456789" \
-                      "+/";
-
-unsigned char *
-encode(unsigned char *op, int np)
-{
-    extern unsigned char s[];
-    unsigned char *sp;
-    int n;
-
-    sp = s;
-    switch (np) {
-        case 3:
-            *sp++ = b64[(*op & ~3) >> 2];
-            n = (*op++ & 3) << 4;
-            *sp++ = b64[n + ((*op & ~15) >> 4)];
-            n = (*op++ & 15) << 2;
-            *sp++ = b64[n + ((*op & 192) >> 6)];
-            *sp = b64[*op & ~192];
-            break;
-        case 2:
-            *sp++ = b64[(*op & ~3) >> 2];
-            n = (*op++ & 3) << 4;
-            *sp++ = b64[n + ((*op & ~15) >> 4)];
-            *sp++ = b64[(*op & 15) << 2];
-            *sp = PADDING;
-            break;
-        case 1:
-            *sp++ = b64[(*op & ~3) >> 2];
-            *sp++ = b64[(*op & 3) << 4];
-            *sp++ = PADDING;
-            *sp = PADDING;
-            break;
-    }
-
-    return s;
-}
-
-unsigned char *
-decode(unsigned char *sp, int *np)
-{
-    extern unsigned char o[];
-    unsigned char *op;
-    int n, b, atob(int c);
-
-    op = o;
-    switch (*np) {
-        case 4:
-            n = atob(*sp++) << 2;
-            b = atob(*sp++);
-            *op++ = n + ((b & ~15) >> 4);
-
-            n = (b & 15) << 4;
-            b = atob(*sp++);
-            *op++ = n + ((b & ~3) >> 2);
-
-            *op = ((b & 3) << 6) + atob(*sp);
-            break;
-        case 3:
-            n = atob(*sp++) << 2;
-            b = atob(*sp++);
-            *op++ = n + ((b & ~15) >> 4);
-
-            n = (b & 15) << 4;
-            *op = n + ((atob(*sp) & ~3) >> 2);
-            break;
-        case 2:
-            n = atob(*sp++) << 2;
-            *op = n + ((atob(*sp) & ~15) >> 4);
-            break;
-    }
-    *np = op-o+1;
-
-    return o;
-}
-
-int atob(int c)
-{
-    if (c >= 'A' && c <= 'Z')
-        c -= 'A';
-    else if (c >= 'a' && c <= 'z')
-        c = c - 'a' + 26;
-    else if (c >= '0' && c <= '9')
-        c = c - '0' + 26 * 2;
-    else if (c == '+')
-        c = 62;
-    else
-        c = 63;
-
-    return c;
-}
diff --git a/trans.h b/trans.h
deleted file mode 100644
index 845a2d2..0000000
--- a/trans.h
+++ /dev/null
@@ -1,12 +0,0 @@
-#ifndef HEADER_TRANS
-#define HEADER_TRANS
-
-#include "input.h"
-
-unsigned char *
-encode(unsigned char *op, int np);
-
-unsigned char *
-decode(unsigned char *sp, int *np);
-
-#endif