diff --git a/walk/walk.c b/walk/walk.c
index 301cf9e..10dbde7 100644
--- a/walk/walk.c
+++ b/walk/walk.c
@@ -35,7 +35,7 @@
 
 #include <errno.h> /* errno */
 #include <stdio.h> /* fprintf(3), perror(3), stderr, stdout */
-#include <stdlib.h> /* realloc(3) */
+#include <stdlib.h> /* free(3), realloc(3) */
 #include <string.h> /* stpcpy(3), strcmp(3), strerror(3), strlen(3) */
 #if !defined EX_OK || !defined EX_INVALID || !defined EX_OSERR \
 		 || !defined EX_USAGE
@@ -45,6 +45,7 @@
 #include <dirent.h> /* closedir(3), opendir(3), readdir(3), DIR,
                      * struct dirent */
 
+static char *program_name = "<no argv[0]>";
 static char *dot[] = {".", NULL}; /* default (argc<2) */
 
 static char *nul_terminator = "\0";
@@ -67,7 +68,7 @@ static int
 walk(char *dirname, char *argv0){
 	DIR *dir;
 	struct dirent *f;
-	static struct { size_t a; char *s; } filename = { 0, NULL };
+	struct { size_t a; char *s; } filename = { 0, NULL };
 	size_t l;
 	char *np;
 	int retval;
@@ -83,8 +84,10 @@ walk(char *dirname, char *argv0){
 		if(strcmp(f->d_name, ".") == 0 || strcmp(f->d_name, "..") == 0)
 			continue;
 		if((l = strlen(dirname) + 1 + strlen(f->d_name) + 1) > filename.a){
-			if((np = realloc(filename.s, l)) == NULL)
+			if((np = realloc(filename.s, l)) == NULL){
+				free(filename.s);
 				return EX_OSERR;
+			}
 			filename.a = l;
 			filename.s = np;
 		}
@@ -94,13 +97,14 @@ walk(char *dirname, char *argv0){
 		 * directory. */
 		if(f->d_type == DT_DIR || f->d_type == DT_UNKNOWN){
 			if((retval = walk(filename.s, argv0)) != EX_OK){
-				if(retval == EX_OSERR)
+				if(retval == EX_OSERR){
+					free(filename.s);
 					return retval;
+				}
 				else if(retval != EX_NOINPUT)
 					fprintf(stderr, "%s: %s: %s\n",
 						argv0, filename.s, strerror(errno));
-			}else
-				fnprint(filename.s);
+			}
 		}else
 			fnprint(filename.s);
 	}
@@ -108,6 +112,7 @@ walk(char *dirname, char *argv0){
 	if(errno != 0 || closedir(dir) != 0)
 		fprintf(stderr, "%s: %s: %s\n", argv0, dirname, strerror(errno));
 
+	free(filename.s);
 	return EX_OK;
 }
 
@@ -116,7 +121,7 @@ int main(int argc, char *argv[]){
 	int c;
 	int retval;
 
-	argv0 = argv[0];
+	argv0 = argv[0] == NULL ? program_name : argv[0];
 	terminator = asv_terminator;
 
 	if(argc > 0){