diff --git a/include/asm/lexer.hpp b/include/asm/lexer.hpp
index a282bbe92..535c15a43 100644
--- a/include/asm/lexer.hpp
+++ b/include/asm/lexer.hpp
@@ -15,11 +15,11 @@
 
 // This value is a compromise between `LexerState` allocation performance when `mmap` works, and
 // buffering performance when it doesn't/can't (e.g. when piping a file into RGBASM).
-#define LEXER_BUF_SIZE 64
+static constexpr size_t lexer_buf_size = 64;
 // The buffer needs to be large enough for the maximum `lexerState->peek()` lookahead distance
-static_assert(LEXER_BUF_SIZE > 1, "Lexer buffer size is too small");
+static_assert(lexer_buf_size > 1, "Lexer buffer size is too small");
 // This caps the size of buffer reads, and according to POSIX, passing more than SSIZE_MAX is UB
-static_assert(LEXER_BUF_SIZE <= SSIZE_MAX, "Lexer buffer size is too large");
+static_assert(lexer_buf_size <= SSIZE_MAX, "Lexer buffer size is too large");
 
 enum LexerMode {
 	LEXER_NORMAL,
@@ -58,7 +58,7 @@ struct ViewedContent {
 
 struct BufferedContent {
 	int fd;                        // File from which to read chars
-	char buf[LEXER_BUF_SIZE] = {}; // Circular buffer of chars
+	char buf[lexer_buf_size] = {}; // Circular buffer of chars
 	size_t offset = 0;             // Cursor into `buf`
 	size_t size = 0;               // Number of "fresh" chars in `buf`
 
diff --git a/src/asm/lexer.cpp b/src/asm/lexer.cpp
index 5290eaa34..aa8e12878 100644
--- a/src/asm/lexer.cpp
+++ b/src/asm/lexer.cpp
@@ -19,7 +19,7 @@
 	#include <unistd.h>
 #endif
 
-#include "helpers.hpp" // assume, QUOTEDSTRLEN
+#include "helpers.hpp"
 #include "util.hpp"
 
 #include "asm/fixpoint.hpp"
@@ -500,27 +500,27 @@ BufferedContent::~BufferedContent() {
 }
 
 void BufferedContent::advance() {
-	assume(offset < LEXER_BUF_SIZE);
+	assume(offset < ARRAY_SIZE(buf));
 	offset++;
-	if (offset == LEXER_BUF_SIZE)
+	if (offset == ARRAY_SIZE(buf))
 		offset = 0; // Wrap around if necessary
 	assume(size > 0);
 	size--;
 }
 
 void BufferedContent::refill() {
-	size_t target = LEXER_BUF_SIZE - size; // Aim: making the buf full
+	size_t target = ARRAY_SIZE(buf) - size; // Aim: making the buf full
 
 	// Compute the index we'll start writing to
-	size_t startIndex = (offset + size) % LEXER_BUF_SIZE;
+	size_t startIndex = (offset + size) % ARRAY_SIZE(buf);
 
 	// If the range to fill passes over the buffer wrapping point, we need two reads
-	if (startIndex + target > LEXER_BUF_SIZE) {
-		size_t nbExpectedChars = LEXER_BUF_SIZE - startIndex;
+	if (startIndex + target > ARRAY_SIZE(buf)) {
+		size_t nbExpectedChars = ARRAY_SIZE(buf) - startIndex;
 		size_t nbReadChars = readMore(startIndex, nbExpectedChars);
 
 		startIndex += nbReadChars;
-		if (startIndex == LEXER_BUF_SIZE)
+		if (startIndex == ARRAY_SIZE(buf))
 			startIndex = 0;
 
 		// If the read was incomplete, don't perform a second read
@@ -534,7 +534,7 @@ void BufferedContent::refill() {
 
 size_t BufferedContent::readMore(size_t startIndex, size_t nbChars) {
 	// This buffer overflow made me lose WEEKS of my life. Never again.
-	assume(startIndex + nbChars <= LEXER_BUF_SIZE);
+	assume(startIndex + nbChars <= ARRAY_SIZE(buf));
 	ssize_t nbReadChars = read(fd, &buf[startIndex], nbChars);
 
 	if (nbReadChars == -1)
@@ -720,7 +720,7 @@ int LexerState::peekChar() {
 		auto &cbuf = content.get<BufferedContent>();
 		if (cbuf.size == 0)
 			cbuf.refill();
-		assume(cbuf.offset < LEXER_BUF_SIZE);
+		assume(cbuf.offset < ARRAY_SIZE(cbuf.buf));
 		if (cbuf.size > 0)
 			return static_cast<uint8_t>(cbuf.buf[cbuf.offset]);
 	}
@@ -748,11 +748,11 @@ int LexerState::peekCharAhead() {
 			return static_cast<uint8_t>(view.span.ptr[view.offset + distance]);
 	} else {
 		auto &cbuf = content.get<BufferedContent>();
-		assume(distance < LEXER_BUF_SIZE);
+		assume(distance < ARRAY_SIZE(cbuf.buf));
 		if (cbuf.size <= distance)
 			cbuf.refill();
 		if (cbuf.size > distance)
-			return static_cast<uint8_t>(cbuf.buf[(cbuf.offset + distance) % LEXER_BUF_SIZE]);
+			return static_cast<uint8_t>(cbuf.buf[(cbuf.offset + distance) % ARRAY_SIZE(cbuf.buf)]);
 	}
 
 	// If there aren't enough chars, give up
diff --git a/test/asm/ff00+c.asm b/test/asm/ff00+c.asm
index f03f3fc23..a32f764cb 100644
--- a/test/asm/ff00+c.asm
+++ b/test/asm/ff00+c.asm
@@ -1,5 +1,5 @@
 SECTION "test", ROM0[0]
 	ldh [ $ff00 + c ], a
-	; 257 spaces exceeds both LEXER_BUF_SIZE (42) and uint8_t limit (255)
+	; 257 spaces exceeds both lexer_buf_size (64) and uint8_t limit (255)
 	ldh [ $ff00 +                                                                                                                                                                                                                                                                 c ], a
 	ldh [ $ff00                                                                                                                                                                                                                                                                 + c ], a