diff --git a/src/apps/fits_utils.cpp b/src/apps/fits_utils.cpp
index 4d31886..019cb53 100644
--- a/src/apps/fits_utils.cpp
+++ b/src/apps/fits_utils.cpp
@@ -127,7 +127,7 @@ Image from_fits(const std::string &filename, PixelScale &pixel_scale)
 static
 void write_header(std::ofstream &f, const char *header) {
 	char hdr[81];
-	std::sprintf(hdr, "%-80s", header);
+	std::snprintf(hdr, 81, "%-80s", header);
 	f.write(hdr, 80);
 };
 
@@ -135,7 +135,7 @@ template <typename ...Ts>
 static
 void write_header(std::ofstream &f, const char *fmt, Ts&&...values) {
 	char hdr[81];
-	std::sprintf(hdr, fmt, std::forward<Ts>(values)...);
+	std::snprintf(hdr, 81, fmt, std::forward<Ts>(values)...);
 	write_header(f, hdr);
 };
 
diff --git a/src/apps/profit-cli.cpp b/src/apps/profit-cli.cpp
index 2e812d3..967cd2a 100644
--- a/src/apps/profit-cli.cpp
+++ b/src/apps/profit-cli.cpp
@@ -176,7 +176,7 @@ void show_version(std::ostream &os) {
 	os << endl;
 }
 
-static const char *help_msg = R"===(
+static const char *help_msg_fmt = R"===(
 %s: utility program to generate an image out of a model and a set of profiles
 
 This program is licensed under the GPLv3 license.
@@ -247,10 +247,10 @@ For more information visit https://libprofit.readthedocs.io.
 template <typename T>
 static
 void usage(std::basic_ostream<T> &os, char *prog_name) {
-	char *buff = new char[std::strlen(help_msg) - 4 + std::strlen(prog_name) * 2 + 1];
-	std::sprintf(buff, help_msg, prog_name, prog_name);
+	std::size_t bufsize = std::strlen(help_msg_fmt) - 4 + std::strlen(prog_name) * 2;
+	std::string buff(bufsize, 0);
+	std::snprintf(&buff[0], bufsize, help_msg_fmt, prog_name, prog_name);
 	os << buff;
-	delete []buff;
 }
 
 static