diff --git a/src/mm.c b/src/mm.c
index a9c45b3..56b8c95 100644
--- a/src/mm.c
+++ b/src/mm.c
@@ -82,8 +82,7 @@ Files_append(struct Files *files, FILE *file, char *name) {
  * appropriate for an OS error. */
 static int
 oserr(char *s, char *r) {
-
-	fprintf(stderr, "%s: %s: %s\n", s, r, strerror(errno));
+	(void)fprintf(stderr, "%s: %s: %s\n", s, r, strerror(errno));
 
 	return EX_OSERR;
 }
@@ -100,11 +99,7 @@ usage(char *argv0) {
 }
 
 int main(int argc, char *argv[]) {
-	int c;
 	struct Files files[2]; /* {read, write} */
-	size_t i;
-	size_t j;
-	size_t k; /* loop index but also unbuffer status */
 	int retval;
 
 	/* Initializes the files structs with their default values, standard
@@ -112,39 +107,41 @@ int main(int argc, char *argv[]) {
 	 * these initial values will be overwritten, so to, say, use mm(1)
 	 * equivalently to tee(1p), -o - will need to be specified before
 	 * additional files to ensure standard output is still written. */
-	for (i = 0; i < 2; ++i) {
+	for (size_t i = 0; i < 2; ++i) {
 		files[i].a = 0;
 		files[i].s = 0;
 		files[i].mode = fmode[i];
 		files[i].files = NULL;
 		files[i].names = NULL;
 
-		Files_append(
-			&files[i],
-			i == 0 ? stdin : stdout,
-			i == 0 ? stdin_name : stdout_name
-		);
+		if (Files_append(
+					&files[i],
+					i == 0 ? stdin : stdout,
+					i == 0 ? stdin_name : stdout_name
+				) == NULL) {
+			return oserr(program_name, i == 0 ? stdin_name : stdout_name);
+		}
 
 		files[i].s = 0;
 	}
 
-	k = 0;
-
 	if (argc > 0) {
+		int c;
+		char unbuffered = 0;
+
 		program_name = argv[0];
 
 		while ((c = getopt(argc, argv, "aehi:no:u")) != -1) {
-			switch (c){
+			switch (c) {
 				case 'a': /* "rb+" -> "ab" */
 					files[1].mode[0] = 'a';
 					files[1].mode[2] = '\0';
 					break;
 				case 'e':
-					if (Files_append(&files[1], stderr, stderr_name) != NULL) {
-						break;
+					if (Files_append(&files[1], stderr, stderr_name) == NULL) {
+						return oserr(program_name, stderr_name);
 					}
-
-					return oserr(program_name, "-e");
+					break;
 				case 'i':
 					if (
 						(strcmp(optarg, "-") == 0
@@ -171,16 +168,28 @@ int main(int argc, char *argv[]) {
 
 					return oserr(program_name, optarg);
 				case 'n':
-					if (signal(SIGINT, SIG_IGN) != SIG_ERR) { break; }
+					if (signal(SIGINT, SIG_IGN) == SIG_ERR) {
+						return oserr(program_name, "-n");
+					}
 
-					return oserr(program_name, "-n");
-				case 'u':
-					k = 1;
 					break;
-				default:
-					return usage(program_name);
+				case 'u': unbuffered = 1; break;
+				default: return usage(program_name);
 			}
 		}
+
+		if (unbuffered) { /* Unbuffer files. */
+			for (
+				size_t i = 0;
+				i < files[0].s;
+				setvbuf(files[0].files[i++], NULL, _IONBF, 0)
+			);
+			for (
+				size_t i = 0;
+				i < files[1].s;
+				setvbuf(files[1].files[i++], NULL, _IONBF, 0)
+			);
+		}
 	}
 
 	if (optind != argc) { return usage(program_name); }
@@ -188,26 +197,18 @@ int main(int argc, char *argv[]) {
 	files[0].s += files[0].s == 0;
 	files[1].s += files[1].s == 0;
 	
-	/* Unbuffer files. */
-	if (k) {
-		for (
-			i = 0; i < files[0].s; setvbuf(files[0].files[i++], NULL, _IONBF, 0)
-		);
-		for (
-			i = 0; i < files[1].s; setvbuf(files[1].files[i++], NULL, _IONBF, 0)
-		);
-	}
 
 	retval = EX_OK;
 
 	/* Actual program loop. */
-	for (i = 0; i < files[0].s; ++i) { /* iterate ins */
+	for (size_t i = 0; i < files[0].s; ++i) { /* iterate ins */
+		int c;
+
 		while ((c = getc(files[0].files[i])) != EOF) { /* iterate chars */
-			for (j = 0; j < files[1].s; ++j) { /* iterate outs */
-				if (putc(c, files[1].files[j]) == EOF) {
-					/* notebook's full */
+			for (size_t j = 0; j < files[1].s; ++j) { /* iterate outs */
+				if (putc(c, files[1].files[j]) == EOF) { /* notebook's full */
 					retval = EX_IOERR;
-					fprintf(
+					(void)fprintf(
 						stderr,
 						"%s: %s: %s\n",
 						program_name,
@@ -216,7 +217,7 @@ int main(int argc, char *argv[]) {
 					);
 
 					if (fclose(files[1].files[j]) == EOF) {
-						fprintf(
+						(void)fprintf(
 							stderr,
 							"%s: %s: %s\n",
 							program_name,
@@ -226,7 +227,7 @@ int main(int argc, char *argv[]) {
 					}
 
 					/* massage out the tense muscle */
-					for(k = j--; k < files[1].s - 1; ++k){
+					for(size_t k = j--; k < files[1].s - 1; ++k){
 						files[1].files[k] = files[1].files[k+1];
 						files[1].names[k] = files[1].names[k+1];
 					}