diff --git a/src/tools/ainedit/asm_lexer.l b/src/tools/ainedit/asm_lexer.l
index 9c58bb0..a22ca41 100644
--- a/src/tools/ainedit/asm_lexer.l
+++ b/src/tools/ainedit/asm_lexer.l
@@ -28,6 +28,9 @@
 char string_buf[65536];
 char *string_buf_ptr;
 
+unsigned long asm_line = 1;
+extern void yyerror(const char *s);
+
 %}
 
 %option noyywrap
@@ -39,8 +42,8 @@ id_char  [^ \t\r\n:;\"]
 %%
 
 [ \t]                     ;
-;[^\n]*\n                 return NEWLINE;
-\n                        return NEWLINE;
+;[^\n]*\n                 asm_line++; return NEWLINE;
+\n                        asm_line++; return NEWLINE;
 [a-zA-Z0-9_-]+:           yylval.string = make_string(yytext, yyleng-1); return LABEL;
 ({id_char}|:)*{id_char}+  yylval.string = make_string(yytext, yyleng);   return IDENTIFIER;
 
@@ -55,7 +58,7 @@ id_char  [^ \t\r\n:;\"]
         return IDENTIFIER;
     }
 
-    \n ERROR("Unterminated string literal");
+    \n yyerror("Unterminated string literal");
 
     \\n  *string_buf_ptr++ = '\n';
     \\t  *string_buf_ptr++ = '\t';
@@ -72,4 +75,6 @@ id_char  [^ \t\r\n:;\"]
     }
 }
 
+. return INVALID_TOKEN;
+
 %%
diff --git a/src/tools/ainedit/asm_parser.y b/src/tools/ainedit/asm_parser.y
index 1afc7d6..43bb94a 100644
--- a/src/tools/ainedit/asm_parser.y
+++ b/src/tools/ainedit/asm_parser.y
@@ -37,7 +37,15 @@
 #include "system4/string.h"
 
 extern int yylex();
-void yyerror(const char *s) { ERROR("%s", s); }
+extern unsigned long asm_line;
+
+#define PARSE_ERROR(fmt, ...)						\
+    sys_error("ERROR: At line %d: " fmt "\n", asm_line-1, ##__VA_ARGS__)
+
+void yyerror(const char *s)
+{
+    sys_error("ERROR: At line %d: %s\n", asm_line, s);
+}
 
 static uint32_t instr_ptr;
 
@@ -63,7 +71,7 @@ static struct parse_instruction *make_instruction(struct string *name, parse_arg
     // check opcode
     const struct instruction *info = asm_get_instruction(name->text);
     if (!info)
-        ERROR("Invalid instruction: %s", name->text);
+        PARSE_ERROR("Invalid instruction: %s", name->text);
     // check argument count
     size_t nr_args = args ? kv_size(*args) : 0;
     if (nr_args != (size_t)info->nr_args) {
@@ -72,8 +80,8 @@ static struct parse_instruction *make_instruction(struct string *name, parse_arg
             fprintf(stderr, " %s", kv_A(*args, i)->text);
         }
         fprintf(stderr, "'\n");
-        ERROR("Wrong number of arguments for instruction '%s' (expected %d; got %lu)",
-              name->text, info->nr_args, nr_args);
+        PARSE_ERROR("Wrong number of arguments for instruction '%s' (expected %d; got %lu)",
+                    name->text, info->nr_args, nr_args);
     }
     // NOTE: argument values checked on second pass
 
@@ -112,7 +120,7 @@ static void push_label(char *name)
 %}
 
 %token	<string>	IDENTIFIER LABEL
-%token	<token>		NEWLINE
+%token	<token>		NEWLINE INVALID_TOKEN
 
 %type	<program>	lines
 %type	<instr>		line
diff --git a/src/tools/ainedit/text_lexer.l b/src/tools/ainedit/text_lexer.l
index 52511c6..4da6556 100644
--- a/src/tools/ainedit/text_lexer.l
+++ b/src/tools/ainedit/text_lexer.l
@@ -28,6 +28,9 @@
 char string_buf[65536];
 char *string_buf_ptr;
 
+unsigned long text_line = 1;
+extern void text_error(const char *s);
+
 %}
 
 %option noyywrap
@@ -38,8 +41,8 @@ char *string_buf_ptr;
 %%
 
 [ \t]                     ;
-;[^\n]*\n                 return NEWLINE;
-\n                        return NEWLINE;
+;[^\n]*\n                 text_line++; return NEWLINE;
+\n                        text_line++; return NEWLINE;
 \[                        return LBRACKET;
 \]                        return RBRACKET;
 =                         return EQUAL;
@@ -59,7 +62,7 @@ s                         return STRINGS;
         return STRING;
     }
 
-    \n ERROR("Unterminated string literal");
+    \n text_error("Unterminated string literal");
 
     \\n  *string_buf_ptr++ = '\n';
     \\t  *string_buf_ptr++ = '\t';
@@ -76,4 +79,6 @@ s                         return STRINGS;
     }
 }
 
+. return INVALID_TOKEN;
+
 %%
diff --git a/src/tools/ainedit/text_parser.y b/src/tools/ainedit/text_parser.y
index adccc42..ff3c446 100644
--- a/src/tools/ainedit/text_parser.y
+++ b/src/tools/ainedit/text_parser.y
@@ -30,7 +30,12 @@
 #include "system4/string.h"
 
 extern int text_lex();
-void text_error(const char *s) { ERROR("%s", s); }
+extern unsigned long text_line;
+
+void text_error(const char *s)
+{
+    sys_error("ERROR: At line %lu: %s\n", text_line, s);
+}
 
 static assignment_list *make_program(void)
 {
@@ -55,7 +60,7 @@ static struct text_assignment *make_assignment(int type, int index, struct strin
 
 %}
 
-%token	<token>		NEWLINE LBRACKET RBRACKET EQUAL MESSAGES STRINGS
+%token	<token>		NEWLINE LBRACKET RBRACKET EQUAL MESSAGES STRINGS INVALID_TOKEN
 %token	<integer>	NUMBER
 %token	<string>	STRING
 
diff --git a/src/tools/ex/ex_lexer.l b/src/tools/ex/ex_lexer.l
index 44bac0a..de3f6bf 100644
--- a/src/tools/ex/ex_lexer.l
+++ b/src/tools/ex/ex_lexer.l
@@ -41,6 +41,7 @@ struct string *make_string_from_utf8(const char *str, size_t len)
 }
 
 unsigned long yex_line = 1;
+extern void yex_error(const char *s);
 
 %}
 
@@ -90,7 +91,7 @@ tree                      return TREE;
         return CONST_STRING;
     }
 
-    \n ERROR("Unterminated string literal");
+    \n yex_error("Unterminated string literal");
 
     \\n  *string_buf_ptr++ = '\n';
     \\t  *string_buf_ptr++ = '\t';
diff --git a/src/tools/ex/ex_parser.y b/src/tools/ex/ex_parser.y
index 7a12712..20f80fd 100644
--- a/src/tools/ex/ex_parser.y
+++ b/src/tools/ex/ex_parser.y
@@ -43,7 +43,11 @@
 
 extern int yex_lex();
 extern unsigned long yex_line;
-void yex_error(const char *s) { ERROR("at line %lu: %s", yex_line, s); }
+
+void yex_error(const char *s)
+{
+    sys_error("ERROR: at line %lu: %s\n", yex_line, s);
+}
 
 %}