diff --git a/puer.c b/puer.c
index 3f9880a..ba3afca 100644
--- a/puer.c
+++ b/puer.c
@@ -543,20 +543,57 @@ ssize_t passphrase_prompt(unsigned char *passphrase, size_t size, const char *pr
 	return index - 1;
 }
 
+ssize_t passphrase_file(char *passfile, unsigned char passphrase[], size_t size) {
+	int file = open(passfile, O_RDONLY);
+
+	// Read until newline
+	size_t index = 0;
+	for (;;) {
+		if (index >= size) {
+			fprintf(stderr, "Passphrase too long, maximum size is %zu bytes\n", size - 1);
+			close(file);
+			return -1;
+		}
+
+		ssize_t bytes_read = read(file, &passphrase[index], size - index);
+		if (bytes_read == -1) {
+			perror("Failed to read passphrase");
+			close(file);
+			return -1;
+		} else if (bytes_read == 0) {
+			fprintf(stderr, "Unexpected EOF\n");
+			close(file);
+			return -1;
+		}
+
+		index += bytes_read;
+		if (passphrase[index-1] == '\n') {
+			// Got end of line
+			break;
+		}
+	}
+
+	close(file);
+
+	return index - 1;
+}
+
 void usage(char *name) {
-	fprintf(stderr, "Usage: %s -d | -e [-f]\n\n", name);
+	fprintf(stderr, "Usage: %s -d | -e [-f] [-p passfile]\n\n", name);
 	fprintf(stderr, "-d Decrypt\n");
 	fprintf(stderr, "-e Encrypt\n");
 	fprintf(stderr, "-f Force output to terminal\n");
+	fprintf(stderr, "-p Read passphrase from a file instead of the terminal.\n");
 }
 
 int main(int argc, char *argv[]) {
 	bool encrypting = false;
 	bool decrypting = false;
 	bool force = false;
+	char *passfile = NULL;
 
 	int opt;
-	while ((opt = getopt(argc, argv, "def")) != -1) {
+	while ((opt = getopt(argc, argv, "defp:")) != -1) {
 		switch (opt) {
 			case 'd':
 				decrypting = true;
@@ -567,12 +604,20 @@ int main(int argc, char *argv[]) {
 			case 'f':
 				force = true;
 				break;
+			case 'p':
+				passfile = optarg;
+				break;
 			default:
 				usage(argv[0]);
 				exit(1);
 		}
 	}
 
+	if (optind != argc) {
+		usage(argv[0]);
+		exit(1);
+	}
+
 	if ((!encrypting && !decrypting) || (encrypting && decrypting)) {
 		usage(argv[0]);
 		exit(1);
@@ -609,30 +654,40 @@ int main(int argc, char *argv[]) {
 
 	// Read passphrase
 	unsigned char passphrase[128];
-	ssize_t passphrase_len = passphrase_prompt(passphrase, sizeof(passphrase), "passphrase: ");
-	if (passphrase_len == -1) {
-		explicit_bzero(passphrase, sizeof(passphrase));
-		exit(1);
-	}
-
-	if (encrypting) {
-		// Have the user confirm the passphrase if encrypting, to avoid losing data
-		unsigned char confirm[128];
-		ssize_t confirm_len = passphrase_prompt(confirm, sizeof(confirm), "confirm passphrase: ");
-		if (confirm_len == -1) {
+	ssize_t passphrase_len;
+	if (passfile == NULL) {
+		// Read from terminal if no passfile specified
+		passphrase_len = passphrase_prompt(passphrase, sizeof(passphrase), "passphrase: ");
+		if (passphrase_len == -1) {
 			explicit_bzero(passphrase, sizeof(passphrase));
-			explicit_bzero(confirm, sizeof(confirm));
 			exit(1);
 		}
 
-		if (confirm_len != passphrase_len || memcmp(passphrase, confirm, passphrase_len) != 0) {
-			fprintf(stderr, "Passphrases do not match\n");
-			explicit_bzero(passphrase, sizeof(passphrase));
+		if (encrypting) {
+			// Have the user confirm the passphrase if encrypting, to avoid losing data
+			unsigned char confirm[sizeof(passphrase)];
+			ssize_t confirm_len = passphrase_prompt(confirm, sizeof(confirm), "confirm passphrase: ");
+			if (confirm_len == -1) {
+				explicit_bzero(passphrase, sizeof(passphrase));
+				explicit_bzero(confirm, sizeof(confirm));
+				exit(1);
+			}
+
+			if (confirm_len != passphrase_len || memcmp(passphrase, confirm, passphrase_len) != 0) {
+				fprintf(stderr, "Passphrases do not match\n");
+				explicit_bzero(passphrase, sizeof(passphrase));
+				explicit_bzero(confirm, sizeof(confirm));
+				exit(1);
+			}
+
 			explicit_bzero(confirm, sizeof(confirm));
+		}
+	} else {
+		passphrase_len = passphrase_file(passfile, passphrase, sizeof(passphrase));
+		if (passphrase_len == -1) {
+			explicit_bzero(passphrase, sizeof(passphrase));
 			exit(1);
 		}
-
-		explicit_bzero(confirm, sizeof(confirm));
 	}
 
 	// Derive key