diff --git a/src/debug.c b/src/debug.c
index 15a99fe..33b8f38 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -26,6 +26,7 @@
 #include <stdio.h>
 #include <errno.h>
 #include <stdarg.h>
+#include <regex.h>
 
 #include "libzzuf.h"
 #include "debug.h"
diff --git a/src/fuzz.c b/src/fuzz.c
index 188d3cc..688145c 100644
--- a/src/fuzz.c
+++ b/src/fuzz.c
@@ -25,6 +25,7 @@
 #endif
 #include <stdio.h>
 #include <string.h>
+#include <regex.h>
 
 #include "libzzuf.h"
 #include "debug.h"
diff --git a/src/libzzuf.c b/src/libzzuf.c
index e6c276d..1c542f4 100644
--- a/src/libzzuf.c
+++ b/src/libzzuf.c
@@ -29,6 +29,7 @@
 #include <stdlib.h>
 #include <fcntl.h>
 #include <errno.h>
+#include <regex.h>
 
 #include <stdarg.h>
 #include <dlfcn.h>
@@ -41,6 +42,8 @@
 int   _zzuf_debug   = 0;
 int   _zzuf_seed    = 0;
 float _zzuf_percent = 0.04f;
+regex_t * _zzuf_include = NULL;
+regex_t * _zzuf_exclude = NULL;
 
 #define MAXFD 1024
 struct zzuf files[MAXFD];
@@ -70,6 +73,22 @@ void zzuf_init(void)
     else if(_zzuf_percent > 1.0f)
         _zzuf_percent = 1.0f;
 
+    tmp = getenv("ZZUF_INCLUDE");
+    if(tmp && *tmp)
+    {
+        _zzuf_include = malloc(sizeof(*_zzuf_include));
+debug("zzuf_include = \"%s\"", tmp);
+        regcomp(_zzuf_include, tmp, 0);
+    }
+
+    tmp = getenv("ZZUF_EXCLUDE");
+    if(tmp && *tmp)
+    {
+        _zzuf_exclude = malloc(sizeof(*_zzuf_exclude));
+debug("zzuf_exclude = \"%s\"", tmp);
+        regcomp(_zzuf_exclude, tmp, 0);
+    }
+
     for(i = 0; i < MAXFD; i++)
         files[i].managed = 0;
 }
diff --git a/src/libzzuf.h b/src/libzzuf.h
index d51265a..af2174e 100644
--- a/src/libzzuf.h
+++ b/src/libzzuf.h
@@ -30,6 +30,8 @@ extern struct zzuf files[];
 extern int   _zzuf_debug;
 extern int   _zzuf_seed;
 extern float _zzuf_percent;
+extern regex_t * _zzuf_include;
+extern regex_t * _zzuf_exclude;
 
 /* Library initialisation shit */
 extern void zzuf_init(void) __attribute__((constructor));
diff --git a/src/preload.c b/src/preload.c
index bf2f763..2a79e64 100644
--- a/src/preload.c
+++ b/src/preload.c
@@ -29,6 +29,7 @@
 #include <stdlib.h>
 #include <fcntl.h>
 #include <errno.h>
+#include <regex.h>
 
 #include <stdarg.h>
 #include <dlfcn.h>
@@ -77,7 +78,9 @@ int zzuf_preload(void)
     { \
         ret = ORIG(fn)(path, mode); \
         debug(STR(fn) "(\"%s\", \"%s\") = %p", path, mode, ret); \
-        if(ret) \
+        if(ret \
+            && (!_zzuf_include || !regexec(_zzuf_include, path, 0, NULL, 0)) \
+            && (!_zzuf_exclude || regexec(_zzuf_exclude, path, 0, NULL, 0))) \
         { \
             int fd = fileno(ret); \
             files[fd].managed = 1; \
@@ -127,13 +130,13 @@ size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream)
             debug(STR(fn) "(\"%s\", %i) = %i", file, oflag, ret); \
         } \
         \
-        if(ret >= 0) \
+        if(ret >= 0 \
+            && ((oflag & (O_RDONLY | O_RDWR | O_WRONLY)) != O_WRONLY) \
+            && (!_zzuf_include || !regexec(_zzuf_include, file, 0, NULL, 0)) \
+            && (!_zzuf_exclude || regexec(_zzuf_exclude, file, 0, NULL, 0))) \
         { \
-            if((oflag & (O_RDONLY | O_RDWR | O_WRONLY)) != O_WRONLY) \
-            { \
-                files[ret].managed = 1; \
-                files[ret].pos = 0; \
-            } \
+            files[ret].managed = 1; \
+            files[ret].pos = 0; \
         } \
     } while(0)
 
diff --git a/src/zzuf.c b/src/zzuf.c
index 9a8c956..dfbfb69 100644
--- a/src/zzuf.c
+++ b/src/zzuf.c
@@ -41,10 +41,7 @@ static void usage(void);
 
 int main(int argc, char *argv[])
 {
-    char buf[BUFSIZ];
     char **newargv;
-    long int seed = 0;
-    float percent = 0.04;
 
 #if defined(HAVE_GETOPT_H)
     for(;;)
@@ -55,28 +52,36 @@ int main(int argc, char *argv[])
         static struct option long_options[] =
             {
                 /* Long option, needs arg, flag, short option */
+                { "include", 1, NULL, 'i' },
+                { "exclude", 1, NULL, 'e' },
                 { "seed", 1, NULL, 's' },
                 { "percent", 1, NULL, 'p' },
                 { "help", 0, NULL, 'h' },
                 { "version", 0, NULL, 'v' },
             };
 
-        int c = getopt_long(argc, argv, "s:p:hv",
+        int c = getopt_long(argc, argv, "i:e:s:p:hv",
                             long_options, &option_index);
 #   else
 #       define MOREINFO "Try `%s -h' for more information.\n"
-        int c = getopt(argc, argv, "s:p:hv");
+        int c = getopt(argc, argv, "i:e:s:p:hv");
 #   endif
         if(c == -1)
             break;
 
         switch(c)
         {
+        case 'i': /* --include */
+            setenv("ZZUF_INCLUDE", optarg, 1);
+            break;
+        case 'e': /* --exclude */
+            setenv("ZZUF_EXCLUDE", optarg, 1);
+            break;
         case 's': /* --seed */
-            seed = atol(optarg);
+            setenv("ZZUF_SEED", optarg, 1);
             break;
         case 'p': /* --percent */
-            percent = atof(optarg);
+            setenv("ZZUF_PERCENT", optarg, 1);
             break;
         case 'h': /* --help */
             usage();
@@ -109,12 +114,6 @@ int main(int argc, char *argv[])
     /* Preload libzzuf.so */
     set_ld_preload(argv[0]);
 
-    /* Set environment */
-    sprintf(buf, "%lu", (unsigned long int)seed);
-    setenv("ZZUF_SEED", buf, 1);
-    sprintf(buf, "%g", percent);
-    setenv("ZZUF_PERCENT", buf, 1);
-
     /* Call our process */
     execvp(newargv[0], newargv);
 
@@ -149,7 +148,8 @@ static void version(void)
 #if defined(HAVE_GETOPT_H)
 static void usage(void)
 {
-    printf("Usage: zzuf [ -vh ] [ -p percent ] [ -s seed ] PROG ARGS...\n");
+    printf("Usage: zzuf [ -vh ] [ -i regex ] [ -e regex ]\n");
+    printf("                    [ -p percent ] [ -s seed ] PROG ARGS...\n");
 #   ifdef HAVE_GETOPT_LONG
     printf("  -h, --help          display this help and exit\n");
     printf("  -v, --version       output version information and exit\n");