diff --git a/foo.asm b/foo.asm
new file mode 100644
index 00000000..db07d9e6
--- /dev/null
+++ b/foo.asm
@@ -0,0 +1 @@
+println x
diff --git a/foo.inc b/foo.inc
new file mode 100644
index 00000000..7b2bde30
--- /dev/null
+++ b/foo.inc
@@ -0,0 +1 @@
+def x = 42
diff --git a/src/asm/lexer.cpp b/src/asm/lexer.cpp
index 635a5128..9927849a 100644
--- a/src/asm/lexer.cpp
+++ b/src/asm/lexer.cpp
@@ -624,7 +624,7 @@ static uint32_t readBracketedMacroArgNum() {
 	}
 
 	if (c >= '0' && c <= '9') {
-		uint32_t n = readDecimalNumber(0);
+		uint32_t n = readDecimalNumber(bumpChar());
 		if (n > INT32_MAX) {
 			error("Number in bracketed macro argument is too large");
 			return 0;
@@ -1165,11 +1165,11 @@ static uint32_t readOctalNumber() {
 }
 
 static uint32_t readDecimalNumber(int initial) {
-	uint32_t value = initial ? initial - '0' : 0;
-	bool empty = !initial;
+	assume(initial >= '0' && initial <= '9');
+	uint32_t value = initial - '0';
 
 	for (int c = peek();; c = nextChar()) {
-		if (c == '_' && !empty) {
+		if (c == '_') {
 			continue;
 		} else if (c >= '0' && c <= '9') {
 			c = c - '0';
@@ -1181,12 +1181,6 @@ static uint32_t readDecimalNumber(int initial) {
 			warning(WARNING_LARGE_CONSTANT, "Integer constant is too large");
 		}
 		value = value * 10 + c;
-
-		empty = false;
-	}
-
-	if (empty) {
-		error("Invalid integer constant, no digits");
 	}
 
 	return value;
@@ -1393,9 +1387,9 @@ static void appendExpandedString(std::string &str, std::string const &expanded)
 		case '\n':
 			str += "\\n";
 			break;
+			// LCOV_EXCL_START
 		case '\r':
 			// A literal CR in a string may get treated as a LF, so '\r' is not tested.
-			// LCOV_EXCL_START
 			str += "\\r";
 			break;
 			// LCOV_EXCL_STOP
@@ -1637,16 +1631,9 @@ static bool isGarbageCharacter(int c) {
 	       && (c == '\0' || !strchr("; \t~[](),+-*/|^=!<>:&%`\"\r\n\\", c));
 }
 
-static void skipGarbageCharacters(int c) {
+static void reportGarbageCharacters(int c) {
 	// '#' can be garbage if it doesn't start a raw string or identifier
 	assume(isGarbageCharacter(c) || c == '#');
-
-	// Do not report weird characters when capturing, it'll be done later
-	if (lexerState->capturing) {
-		skipChars(isGarbageCharacter);
-		return;
-	}
-
 	if (isGarbageCharacter(peek())) {
 		// At least two characters are garbage; group them into one error report
 		std::string garbage = printChar(c);
@@ -1966,7 +1953,7 @@ static Token yylex_NORMAL() {
 			if (raw && startsIdentifier(peek())) {
 				c = bumpChar();
 			} else if (!startsIdentifier(c)) {
-				skipGarbageCharacters(c);
+				reportGarbageCharacters(c);
 				continue;
 			}
 
diff --git a/src/asm/opt.cpp b/src/asm/opt.cpp
index 8cecf181..61e02cc5 100644
--- a/src/asm/opt.cpp
+++ b/src/asm/opt.cpp
@@ -7,6 +7,8 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include "helpers.hpp" // assume
+
 #include "asm/fixpoint.hpp"
 #include "asm/fstack.hpp"
 #include "asm/lexer.hpp"
@@ -77,9 +79,9 @@ void opt_Parse(char const *s) {
 			result = sscanf(&s[1], "%x", &padByte);
 			if (result != 1) {
 				error("Invalid argument for option 'p'");
-			} else if (padByte > 0xFF) {
-				error("Argument for option 'p' must be between 0 and 0xFF");
 			} else {
+				// Two characters cannot be scanned as a hex number greater than 0xFF
+				assume(padByte <= 0xFF);
 				opt_P(padByte);
 			}
 		} else {
diff --git a/src/asm/rpn.cpp b/src/asm/rpn.cpp
index 7f3028a2..f5670faa 100644
--- a/src/asm/rpn.cpp
+++ b/src/asm/rpn.cpp
@@ -325,9 +325,9 @@ void Expression::makeUnaryOp(RPNCommand op, Expression &&src) {
 		case RPN_TZCOUNT:
 			data = val != 0 ? ctz(uval) : 32;
 			break;
+		// LCOV_EXCL_START
 		default:
 			// `makeUnaryOp` should never be called with a non-unary operator!
-			// LCOV_EXCL_START
 			unreachable_();
 		}
 		// LCOV_EXCL_STOP
@@ -467,9 +467,9 @@ void Expression::makeBinaryOp(RPNCommand op, Expression &&src1, Expression const
 
 			data = op_exponent(lval, rval);
 			break;
+		// LCOV_EXCL_START
 		default:
 			// `makeBinaryOp` should never be called with a non-binary operator!
-			// LCOV_EXCL_START
 			unreachable_();
 		}
 		// LCOV_EXCL_STOP
diff --git a/test/asm/character-literals.asm b/test/asm/character-literals.asm
index f50f146f..ee99ef0e 100644
--- a/test/asm/character-literals.asm
+++ b/test/asm/character-literals.asm
@@ -32,3 +32,4 @@ char '?', $3f ; ASCII
 char 'F', 0
 char 'ABF', 0
 char '\n\r\t', 0
+assert 0 == '
diff --git a/test/asm/character-literals.err b/test/asm/character-literals.err
index b2eaa6f9..a68f4619 100644
--- a/test/asm/character-literals.err
+++ b/test/asm/character-literals.err
@@ -12,4 +12,8 @@ warning: character-literals.asm(34) -> character-literals.asm::char(13): [-Wunma
     Unmapped character '\t'
 error: character-literals.asm(34) -> character-literals.asm::char(13):
     Character literals must be a single charmap unit
-Assembly aborted with 3 errors!
+error: character-literals.asm(35):
+    Unterminated character
+error: character-literals.asm(35):
+    Character literals must be a single charmap unit
+Assembly aborted with 5 errors!
diff --git a/test/asm/include-slash.asm b/test/asm/include-slash.asm
new file mode 100644
index 00000000..db07d9e6
--- /dev/null
+++ b/test/asm/include-slash.asm
@@ -0,0 +1 @@
+println x
diff --git a/test/asm/include-slash.err b/test/asm/include-slash.err
new file mode 100644
index 00000000..a1aa9377
--- /dev/null
+++ b/test/asm/include-slash.err
@@ -0,0 +1,3 @@
+error: include-slash.asm(0):
+    Error reading pre-included file 'include-slash-nonexist.inc': No such file or directory
+Assembly aborted with 1 error!
diff --git a/test/asm/include-slash.flags b/test/asm/include-slash.flags
new file mode 100644
index 00000000..abfee7da
--- /dev/null
+++ b/test/asm/include-slash.flags
@@ -0,0 +1 @@
+-Weverything -P include-slash.inc -I include -P include-slash-nonexist.inc
diff --git a/test/asm/include-slash.out b/test/asm/include-slash.out
new file mode 100644
index 00000000..72555870
--- /dev/null
+++ b/test/asm/include-slash.out
@@ -0,0 +1 @@
+$2A
diff --git a/test/asm/include/include-slash.inc b/test/asm/include/include-slash.inc
new file mode 100644
index 00000000..7b2bde30
--- /dev/null
+++ b/test/asm/include/include-slash.inc
@@ -0,0 +1 @@
+def x = 42
diff --git a/test/asm/state-file/a.asm b/test/asm/state-file/a.asm
index b8e47b31..c9e77adf 100644
--- a/test/asm/state-file/a.asm
+++ b/test/asm/state-file/a.asm
@@ -12,7 +12,7 @@ def variable += 1
 
 def con2 equ -1
 def var2 = variable**2
-def str2 equs strcat("{string}", "\0\n\t\r")
+def str2 equs strcat("{string}", "\0\n\t\r\\\"\{")
 charmap "c2", 10, -11, 987654321
 
 PURGE polo
diff --git a/test/asm/state-file/a.dump.asm b/test/asm/state-file/a.dump.asm
index d3205863..e7079ba1 100644
--- a/test/asm/state-file/a.dump.asm
+++ b/test/asm/state-file/a.dump.asm
@@ -10,7 +10,7 @@ def var2 = $9
 
 ; String constants
 def string equs "goodbye~"
-def str2 equs "hello!\0\n\t\r"
+def str2 equs "hello!\0\n\t\r\\\"\{"
 
 ; Character maps
 newcharmap main
diff --git a/test/asm/update-refs.sh b/test/asm/update-refs.sh
deleted file mode 100755
index 192ff602..00000000
--- a/test/asm/update-refs.sh
+++ /dev/null
@@ -1,10 +0,0 @@
-#!/usr/bin/env bash
-fname=$(mktemp)
-
-for i in *.asm; do
-	../../rgbasm $i >$fname 2>&1
-	mv -f $fname ${i%.asm}.out
-done
-
-rm -f $fname
-exit 0