diff --git a/main/compilation/expression.cpp b/main/compilation/expression.cpp
index cabe9db3..2c87417d 100644
--- a/main/compilation/expression.cpp
+++ b/main/compilation/expression.cpp
@@ -1,4 +1,5 @@
 #include "expression.h"
+#include "../utils/string_utils.h"
 #include <stdexcept>
 
 Expression::Expression(const Type type) : type(type) {
@@ -28,18 +29,18 @@ bool Expression::is_numbery() const {
     return this->type == number || this->type == integer || this->type == boolean;
 }
 
-int Expression::print_to_buffer(char *buffer) const {
+int Expression::print_to_buffer(char *buffer, size_t buffer_len) const {
     switch (this->type) {
     case boolean:
-        return sprintf(buffer, "%s", this->evaluate_boolean() ? "true" : "false");
+        return csprintf(buffer, buffer_len, "%s", this->evaluate_boolean() ? "true" : "false");
     case integer:
-        return sprintf(buffer, "%lld", this->evaluate_integer());
+        return csprintf(buffer, buffer_len, "%lld", this->evaluate_integer());
     case number:
-        return sprintf(buffer, "%f", this->evaluate_number());
+        return csprintf(buffer, buffer_len, "%f", this->evaluate_number());
     case string:
-        return sprintf(buffer, "\"%s\"", this->evaluate_string().c_str());
+        return csprintf(buffer, buffer_len, "\"%s\"", this->evaluate_string().c_str());
     case identifier:
-        return sprintf(buffer, "%s", this->evaluate_identifier().c_str());
+        return csprintf(buffer, buffer_len, "%s", this->evaluate_identifier().c_str());
     default:
         throw std::runtime_error("expression has an invalid datatype");
     }
diff --git a/main/compilation/expression.h b/main/compilation/expression.h
index 4f5a03fe..02b06009 100644
--- a/main/compilation/expression.h
+++ b/main/compilation/expression.h
@@ -10,7 +10,7 @@ class Expression;
 using Expression_ptr = std::shared_ptr<Expression>;
 using ConstExpression_ptr = std::shared_ptr<const Expression>;
 
-int write_arguments_to_buffer(const std::vector<ConstExpression_ptr> arguments, char *buffer);
+int write_arguments_to_buffer(const std::vector<ConstExpression_ptr> arguments, char *buffer, size_t buffer_len);
 
 class Expression {
 protected:
@@ -25,5 +25,5 @@ class Expression {
     virtual std::string evaluate_string() const;
     virtual std::string evaluate_identifier() const;
     bool is_numbery() const;
-    int print_to_buffer(char *buffer) const;
+    int print_to_buffer(char *buffer, size_t buffer_len) const;
 };
diff --git a/main/compilation/expressions.cpp b/main/compilation/expressions.cpp
index 98ea2e2a..7dc106fb 100644
--- a/main/compilation/expressions.cpp
+++ b/main/compilation/expressions.cpp
@@ -1,15 +1,16 @@
 #include "expressions.h"
 #include "../modules/module.h"
+#include "../utils/string_utils.h"
 #include "math.h"
 #include <stdexcept>
 
-int write_arguments_to_buffer(const std::vector<ConstExpression_ptr> arguments, char *buffer) {
+int write_arguments_to_buffer(const std::vector<ConstExpression_ptr> arguments, char *buffer, size_t buffer_len) {
     int pos = 0;
     for (auto const &argument : arguments) {
         if (argument != arguments[0]) {
-            pos += std::sprintf(&buffer[pos], ", ");
+            pos += csprintf(&buffer[pos], buffer_len - pos, ", ");
         }
-        pos += argument->print_to_buffer(&buffer[pos]);
+        pos += argument->print_to_buffer(&buffer[pos], buffer_len - pos);
     }
     return pos;
 }
diff --git a/main/compilation/variable.cpp b/main/compilation/variable.cpp
index 2e18d0de..7d23d64c 100644
--- a/main/compilation/variable.cpp
+++ b/main/compilation/variable.cpp
@@ -1,4 +1,5 @@
 #include "variable.h"
+#include "../utils/string_utils.h"
 #include "expression.h"
 #include <stdexcept>
 
@@ -21,18 +22,18 @@ void Variable::assign(const ConstExpression_ptr expression) {
     }
 }
 
-int Variable::print_to_buffer(char *const buffer) const {
+int Variable::print_to_buffer(char *const buffer, size_t buffer_len) const {
     switch (this->type) {
     case boolean:
-        return sprintf(buffer, "%s", this->boolean_value ? "true" : "false");
+        return csprintf(buffer, buffer_len, "%s", this->boolean_value ? "true" : "false");
     case integer:
-        return sprintf(buffer, "%lld", this->integer_value);
+        return csprintf(buffer, buffer_len, "%lld", this->integer_value);
     case number:
-        return sprintf(buffer, "%f", this->number_value);
+        return csprintf(buffer, buffer_len, "%f", this->number_value);
     case string:
-        return sprintf(buffer, "\"%s\"", this->string_value.c_str());
+        return csprintf(buffer, buffer_len, "\"%s\"", this->string_value.c_str());
     case identifier:
-        return sprintf(buffer, "%s", this->identifier_value.c_str());
+        return csprintf(buffer, buffer_len, "%s", this->identifier_value.c_str());
     default:
         throw std::runtime_error("variable has an invalid datatype");
     }
diff --git a/main/compilation/variable.h b/main/compilation/variable.h
index 46148e1e..1c533c05 100644
--- a/main/compilation/variable.h
+++ b/main/compilation/variable.h
@@ -23,7 +23,7 @@ class Variable {
 
     Variable(const Type type);
     void assign(const ConstExpression_ptr expression);
-    int print_to_buffer(char *const buffer) const;
+    int print_to_buffer(char *const buffer, size_t buffer_len) const;
 };
 
 class BooleanVariable : public Variable {
diff --git a/main/main.cpp b/main/main.cpp
index 6fab2ad0..51e9d49e 100644
--- a/main/main.cpp
+++ b/main/main.cpp
@@ -189,7 +189,7 @@ void process_tree(owl_tree *const tree, bool from_expander) {
         } else if (!statement.expression.empty) {
             const ConstExpression_ptr expression = compile_expression(statement.expression);
             static char buffer[256];
-            expression->print_to_buffer(buffer);
+            expression->print_to_buffer(buffer, sizeof(buffer));
             echo(buffer);
         } else if (!statement.constructor.empty) {
             const struct parsed_constructor constructor = parsed_constructor_get(statement.constructor);
diff --git a/main/modules/can.cpp b/main/modules/can.cpp
index ebea6bde..05542903 100644
--- a/main/modules/can.cpp
+++ b/main/modules/can.cpp
@@ -1,4 +1,5 @@
 #include "can.h"
+#include "../utils/string_utils.h"
 #include "../utils/uart.h"
 #include "driver/twai.h"
 #include <stdexcept>
@@ -97,10 +98,10 @@ bool Can::receive() {
 
     if (this->output_on) {
         static char buffer[256];
-        int pos = std::sprintf(buffer, "%s %03lx", this->name.c_str(), message.identifier);
+        int pos = csprintf(buffer, sizeof(buffer), "%s %03lx", this->name.c_str(), message.identifier);
         if (!(message.flags & TWAI_MSG_FLAG_RTR)) {
             for (int i = 0; i < message.data_length_code; ++i) {
-                pos += std::sprintf(&buffer[pos], ",%02x", message.data[i]);
+                pos += csprintf(&buffer[pos], sizeof(buffer) - pos, ",%02x", message.data[i]);
             }
         }
         echo(buffer);
diff --git a/main/modules/core.cpp b/main/modules/core.cpp
index be30afa8..858d31c2 100644
--- a/main/modules/core.cpp
+++ b/main/modules/core.cpp
@@ -48,9 +48,9 @@ void Core::call(const std::string method_name, const std::vector<ConstExpression
         int pos = 0;
         for (auto const &argument : arguments) {
             if (argument != arguments[0]) {
-                pos += sprintf(&buffer[pos], " ");
+                pos += csprintf(&buffer[pos], sizeof(buffer) - pos, " ");
             }
-            pos += argument->print_to_buffer(&buffer[pos]);
+            pos += argument->print_to_buffer(&buffer[pos], sizeof(buffer) - pos);
         }
         echo(buffer);
     } else if (method_name == "output") {
@@ -173,22 +173,22 @@ std::string Core::get_output() const {
     int pos = 0;
     for (auto const &element : this->output_list) {
         if (pos > 0) {
-            pos += sprintf(&output_buffer[pos], " ");
+            pos += csprintf(&output_buffer[pos], sizeof(output_buffer) - pos, " ");
         }
         const Variable_ptr variable =
             element.module ? element.module->get_property(element.property_name) : Global::get_variable(element.property_name);
         switch (variable->type) {
         case boolean:
-            pos += sprintf(&output_buffer[pos], "%s", variable->boolean_value ? "true" : "false");
+            pos += csprintf(&output_buffer[pos], sizeof(output_buffer) - pos, "%s", variable->boolean_value ? "true" : "false");
             break;
         case integer:
-            pos += sprintf(&output_buffer[pos], "%lld", variable->integer_value);
+            pos += csprintf(&output_buffer[pos], sizeof(output_buffer) - pos, "%lld", variable->integer_value);
             break;
         case number:
-            pos += sprintf(&output_buffer[pos], "%.*f", element.precision, variable->number_value);
+            pos += csprintf(&output_buffer[pos], sizeof(output_buffer) - pos, "%.*f", element.precision, variable->number_value);
             break;
         case string:
-            pos += sprintf(&output_buffer[pos], "\"%s\"", variable->string_value.c_str());
+            pos += csprintf(&output_buffer[pos], sizeof(output_buffer) - pos, "\"%s\"", variable->string_value.c_str());
             break;
         default:
             throw std::runtime_error("invalid type");
diff --git a/main/modules/expander.cpp b/main/modules/expander.cpp
index db2368d7..4f785ea5 100644
--- a/main/modules/expander.cpp
+++ b/main/modules/expander.cpp
@@ -2,6 +2,7 @@
 
 #include "storage.h"
 #include "utils/serial-replicator.h"
+#include "utils/string_utils.h"
 #include "utils/timing.h"
 #include "utils/uart.h"
 #include <cstring>
@@ -36,7 +37,7 @@ Expander::Expander(const std::string name,
             break;
         }
         if (serial->available()) {
-            len = serial->read_line(buffer);
+            len = serial->read_line(buffer, sizeof(buffer));
             strip(buffer, len);
             echo("%s: %s", name.c_str(), buffer);
         }
@@ -46,7 +47,7 @@ Expander::Expander(const std::string name,
 void Expander::step() {
     static char buffer[1024];
     while (this->serial->has_buffered_lines()) {
-        int len = this->serial->read_line(buffer);
+        int len = this->serial->read_line(buffer, sizeof(buffer));
         check(buffer, len);
         this->last_message_millis = millis();
         if (buffer[0] == '!' && buffer[1] == '!') {
@@ -94,9 +95,9 @@ void Expander::call(const std::string method_name, const std::vector<ConstExpres
         }
     } else {
         static char buffer[1024];
-        int pos = std::sprintf(buffer, "core.%s(", method_name.c_str());
-        pos += write_arguments_to_buffer(arguments, &buffer[pos]);
-        pos += std::sprintf(&buffer[pos], ")");
+        int pos = csprintf(buffer, sizeof(buffer), "core.%s(", method_name.c_str());
+        pos += write_arguments_to_buffer(arguments, &buffer[pos], sizeof(buffer) - pos);
+        pos += csprintf(&buffer[pos], sizeof(buffer) - pos, ")");
         this->serial->write_checked_line(buffer, pos);
     }
 }
diff --git a/main/modules/input.cpp b/main/modules/input.cpp
index 93031ffa..608c4ba5 100644
--- a/main/modules/input.cpp
+++ b/main/modules/input.cpp
@@ -1,4 +1,5 @@
 #include "input.h"
+#include "../utils/string_utils.h"
 #include "../utils/uart.h"
 #include <memory>
 #include <stdexcept>
@@ -38,7 +39,7 @@ void Input::call(const std::string method_name, const std::vector<ConstExpressio
 
 std::string Input::get_output() const {
     static char buffer[256];
-    std::sprintf(buffer, "%d", this->get_level());
+    csprintf(buffer, sizeof(buffer), "%d", this->get_level());
     return buffer;
 }
 
diff --git a/main/modules/module.cpp b/main/modules/module.cpp
index bf0c68f5..44d10051 100644
--- a/main/modules/module.cpp
+++ b/main/modules/module.cpp
@@ -1,5 +1,6 @@
 #include "module.h"
 #include "../global.h"
+#include "../utils/string_utils.h"
 #include "../utils/uart.h"
 #include "analog.h"
 #include "bluetooth.h"
@@ -358,11 +359,11 @@ void Module::step() {
     }
     if (this->broadcast && !this->properties.empty()) {
         static char buffer[1024];
-        int pos = sprintf(buffer, "!!");
+        int pos = csprintf(buffer, sizeof(buffer), "!!");
         for (auto const &[property_name, property] : this->properties) {
-            pos += sprintf(&buffer[pos], "%s.%s=", this->name.c_str(), property_name.c_str());
-            pos += property->print_to_buffer(&buffer[pos]);
-            pos += sprintf(&buffer[pos], ";");
+            pos += csprintf(&buffer[pos], sizeof(buffer) - pos, "%s.%s=", this->name.c_str(), property_name.c_str());
+            pos += property->print_to_buffer(&buffer[pos], sizeof(buffer) - pos);
+            pos += csprintf(&buffer[pos], sizeof(buffer) - pos, ";");
         }
         echo(buffer);
     }
diff --git a/main/modules/proxy.cpp b/main/modules/proxy.cpp
index baff1900..1de7c43a 100644
--- a/main/modules/proxy.cpp
+++ b/main/modules/proxy.cpp
@@ -1,4 +1,5 @@
 #include "proxy.h"
+#include "../utils/string_utils.h"
 #include "driver/uart.h"
 #include <memory>
 
@@ -9,19 +10,19 @@ Proxy::Proxy(const std::string name,
              const std::vector<ConstExpression_ptr> arguments)
     : Module(proxy, name), expander(expander) {
     static char buffer[256];
-    int pos = std::sprintf(buffer, "%s = %s(", name.c_str(), module_type.c_str());
-    pos += write_arguments_to_buffer(arguments, &buffer[pos]);
-    pos += std::sprintf(&buffer[pos], "); ");
-    pos += std::sprintf(&buffer[pos], "%s.broadcast()", name.c_str());
+    int pos = csprintf(buffer, sizeof(buffer), "%s = %s(", name.c_str(), module_type.c_str());
+    pos += write_arguments_to_buffer(arguments, &buffer[pos], sizeof(buffer) - pos);
+    pos += csprintf(&buffer[pos], sizeof(buffer) - pos, "); ");
+    pos += csprintf(&buffer[pos], sizeof(buffer) - pos, "%s.broadcast()", name.c_str());
 
     expander->serial->write_checked_line(buffer, pos);
 }
 
 void Proxy::call(const std::string method_name, const std::vector<ConstExpression_ptr> arguments) {
     static char buffer[256];
-    int pos = std::sprintf(buffer, "%s.%s(", this->name.c_str(), method_name.c_str());
-    pos += write_arguments_to_buffer(arguments, &buffer[pos]);
-    pos += std::sprintf(&buffer[pos], ")");
+    int pos = csprintf(buffer, sizeof(buffer), "%s.%s(", this->name.c_str(), method_name.c_str());
+    pos += write_arguments_to_buffer(arguments, &buffer[pos], sizeof(buffer) - pos);
+    pos += csprintf(&buffer[pos], sizeof(buffer) - pos, ")");
     this->expander->serial->write_checked_line(buffer, pos);
 }
 
@@ -31,8 +32,8 @@ void Proxy::write_property(const std::string property_name, const ConstExpressio
     }
     if (!from_expander) {
         static char buffer[256];
-        int pos = std::sprintf(buffer, "%s.%s = ", this->name.c_str(), property_name.c_str());
-        pos += expression->print_to_buffer(&buffer[pos]);
+        int pos = csprintf(buffer, sizeof(buffer), "%s.%s = ", this->name.c_str(), property_name.c_str());
+        pos += expression->print_to_buffer(&buffer[pos], sizeof(buffer) - pos);
         this->expander->serial->write_checked_line(buffer, pos);
     }
     Module::get_property(property_name)->assign(expression);
diff --git a/main/modules/serial.cpp b/main/modules/serial.cpp
index 11e7573f..7d1ff072 100644
--- a/main/modules/serial.cpp
+++ b/main/modules/serial.cpp
@@ -1,4 +1,5 @@
 #include "serial.h"
+#include "utils/string_utils.h"
 #include "utils/uart.h"
 #include <cstring>
 #include <stdexcept>
@@ -55,7 +56,7 @@ void Serial::write_checked_line(const char *message, const int length) const {
     int start = 0;
     for (unsigned int i = 0; i < length + 1; ++i) {
         if (i >= length || message[i] == '\n') {
-            sprintf(checksum_buffer, "@%02x\n", checksum);
+            csprintf(checksum_buffer, sizeof(checksum_buffer), "@%02x\n", checksum);
             uart_write_bytes(this->uart_num, &message[start], i - start);
             uart_write_bytes(this->uart_num, checksum_buffer, 4);
             start = i + 1;
@@ -89,8 +90,20 @@ int Serial::read(uint32_t timeout) const {
     return length > 0 ? data : -1;
 }
 
-int Serial::read_line(char *buffer) const {
+int Serial::read_line(char *buffer, size_t buffer_len) const {
     int pos = uart_pattern_pop_pos(this->uart_num);
+    if (pos >= buffer_len) {
+        if (this->available() < pos) {
+            uart_flush_input(this->uart_num);
+            while (uart_pattern_pop_pos(this->uart_num) > 0)
+                ;
+            throw std::runtime_error("buffer too small, but cannot discard line. flushed serial.");
+        }
+
+        for (int i = 0; i < pos; i++)
+            this->read();
+        throw std::runtime_error("buffer too small. discarded line.");
+    }
     return pos >= 0 ? uart_read_bytes(this->uart_num, (uint8_t *)buffer, pos + 1, 0) : 0;
 }
 
@@ -109,7 +122,7 @@ std::string Serial::get_output() const {
     int byte;
     int pos = 0;
     while ((byte = this->read()) >= 0) {
-        pos += std::sprintf(&buffer[pos], pos == 0 ? "%02x" : " %02x", byte);
+        pos += csprintf(&buffer[pos], sizeof(buffer) - pos, pos == 0 ? "%02x" : " %02x", byte);
     }
     return buffer;
 }
diff --git a/main/modules/serial.h b/main/modules/serial.h
index fca40658..39b5e489 100644
--- a/main/modules/serial.h
+++ b/main/modules/serial.h
@@ -24,7 +24,7 @@ class Serial : public Module {
     int available() const;
     bool has_buffered_lines() const;
     int read(const uint32_t timeout = 0) const;
-    int read_line(char *buffer) const;
+    int read_line(char *buffer, size_t buffer_len) const;
     size_t write(const uint8_t byte) const;
     void write_checked_line(const char *message, const int length) const;
     void flush() const;
diff --git a/main/utils/string_utils.cpp b/main/utils/string_utils.cpp
index 63cbbacf..4ef552b5 100644
--- a/main/utils/string_utils.cpp
+++ b/main/utils/string_utils.cpp
@@ -1,4 +1,6 @@
 #include "string_utils.h"
+#include <stdarg.h>
+#include <stdexcept>
 #include <string>
 
 std::string cut_first_word(std::string &msg, const char delimiter) {
@@ -10,4 +12,19 @@ std::string cut_first_word(std::string &msg, const char delimiter) {
 
 bool starts_with(const std::string haystack, const std::string needle) {
     return haystack.substr(0, needle.length()) == needle;
+}
+
+int csprintf(char *buffer, size_t buffer_len, const char *format, ...) {
+    va_list args;
+
+    va_start(args, format);
+    const int num_chars = std::vsnprintf(buffer, buffer_len, format, args);
+    va_end(args);
+
+    if (num_chars < 0)
+        throw std::runtime_error("encoding error");
+    if (num_chars > buffer_len - 1)
+        throw std::runtime_error("buffer too small");
+
+    return num_chars;
 }
\ No newline at end of file
diff --git a/main/utils/string_utils.h b/main/utils/string_utils.h
index d26801d5..16e71db9 100644
--- a/main/utils/string_utils.h
+++ b/main/utils/string_utils.h
@@ -4,4 +4,6 @@
 
 std::string cut_first_word(std::string &msg, char delimiter = ' ');
 
-bool starts_with(const std::string haystack, const std::string needle);
\ No newline at end of file
+bool starts_with(const std::string haystack, const std::string needle);
+
+int csprintf(char *buffer, size_t buffer_len, const char *format, ...);
\ No newline at end of file
diff --git a/main/utils/uart.cpp b/main/utils/uart.cpp
index 74dd0511..c471b8c7 100644
--- a/main/utils/uart.cpp
+++ b/main/utils/uart.cpp
@@ -6,11 +6,11 @@
 
 void echo(const char *format, ...) {
     static char buffer[1024];
-    int pos = 0;
 
     va_list args;
     va_start(args, format);
-    pos += std::vsnprintf(&buffer[pos], sizeof buffer - pos - 1, format, args);
+    const int num_chars = std::vsnprintf(buffer, sizeof(buffer) - 1, format, args);
+    int pos = std::min(num_chars, static_cast<int>(sizeof(buffer) - 2));
     va_end(args);
 
     pos += std::sprintf(&buffer[pos], "\n");
@@ -30,10 +30,11 @@ void echo(const char *format, ...) {
 }
 
 int strip(char *buffer, int len) {
-    while (buffer[len - 1] == ' ' ||
-           buffer[len - 1] == '\t' ||
-           buffer[len - 1] == '\r' ||
-           buffer[len - 1] == '\n') {
+    while (len > 0 &&
+           (buffer[len - 1] == ' ' ||
+            buffer[len - 1] == '\t' ||
+            buffer[len - 1] == '\r' ||
+            buffer[len - 1] == '\n')) {
         len--;
     }
     buffer[len] = 0;