diff --git a/builtins/array.h b/builtins/array.h
index 84edcb4..65b7028 100644
--- a/builtins/array.h
+++ b/builtins/array.h
@@ -8,11 +8,12 @@
 #include "types.h"
 
 // Convert negative indices to back-indexed without branching: index0 = index + (index < 0)*(len+1)) - 1
-#define $Array_get(type, x, i) ({ const array_t *$arr = x; int64_t $index = (int64_t)(i); \
-                                int64_t $off = $index + ($index < 0) * ($arr->length + 1) - 1; \
-                                if (__builtin_expect($off < 0 || $off >= $arr->length, 0)) \
-                                    fail("Invalid array index: %ld (array has length %ld)\n", $index, $arr->length); \
-                                *(type*)($arr->data + $arr->stride * $off);})
+#define $Array_get(type, x, i, filename, start, end) ({ \
+    const array_t *$arr = x; int64_t $index = (int64_t)(i); \
+    int64_t $off = $index + ($index < 0) * ($arr->length + 1) - 1; \
+    if (__builtin_expect($off < 0 || $off >= $arr->length, 0)) \
+        fail_source(filename, start, end, "Invalid array index: %r (array has length %ld)\n", Int64__as_str(&$index, USE_COLOR, NULL), $arr->length); \
+    *(type*)($arr->data + $arr->stride * $off);})
 #define $Array_get_unchecked(type, x, i) ({ const array_t *$arr = x; int64_t $index = (int64_t)(i); \
                                           int64_t $off = $index + ($index < 0) * ($arr->length + 1) - 1; \
                                           *(type*)($arr->data + $arr->stride * $off);})
diff --git a/builtins/functions.c b/builtins/functions.c
index 4ca91d3..b7e816c 100644
--- a/builtins/functions.c
+++ b/builtins/functions.c
@@ -22,15 +22,32 @@ public const char *SSS_HASH_VECTOR = "sss hash vector --------------------------
 
 public void fail(CORD fmt, ...)
 {
-    va_list args;
-    va_start(args, fmt);
     if (USE_COLOR) fputs("\x1b[31;7m FAIL: \x1b[m ", stderr);
     else fputs("FAIL: ", stderr);
+    va_list args;
+    va_start(args, fmt);
     CORD_vfprintf(stderr, fmt, args);
     va_end(args);
     raise(SIGABRT);
 }
 
+public void fail_source(const char *filename, int64_t start, int64_t end, CORD fmt, ...)
+{
+    if (USE_COLOR) fputs("\n\x1b[31;7m FAIL: \x1b[m ", stderr);
+    else fputs("\nFAIL: ", stderr);
+
+    va_list args;
+    va_start(args, fmt);
+    CORD_vfprintf(stderr, fmt, args);
+    va_end(args);
+
+    file_t *file = filename ? load_file(filename) : NULL;
+    if (filename && file)
+        fprint_span(stderr, file, file->text+start, file->text+end, "\x1b[31;1m", 2, USE_COLOR);
+
+    raise(SIGABRT);
+}
+
 public uint32_t generic_hash(const void *obj, const TypeInfo *type)
 {
     switch (type->tag) {
@@ -123,7 +140,7 @@ static inline char *without_colors(const char *str)
     return buf;
 }
 
-public void __doctest(void *expr, TypeInfo *type, CORD expected, const char *filename, int start, int end)
+public void __doctest(void *expr, TypeInfo *type, CORD expected, const char *filename, int64_t start, int64_t end)
 {
     static file_t *file = NULL;
     if (filename && (file == NULL || strcmp(file->filename, filename) != 0))
@@ -145,10 +162,10 @@ public void __doctest(void *expr, TypeInfo *type, CORD expected, const char *fil
             }
 
             if (!success) {
-                if (filename && file)
-                    fprint_span(stderr, file, file->text+start, file->text+end, "\x1b[31;1m", 2, USE_COLOR);
-                fail(USE_COLOR ? "\x1b[31;1mDoctest failure:\nExpected: \x1b[32;7m%s\x1b[0m\n\x1b[31;1m But got: \x1b[31;7m%s\x1b[0m\n" : "Doctest failure:\nExpected: %s\n But got: %s\n",
-                     expected, expr_str);
+                fail_source(filename, start, end, 
+                            USE_COLOR ? "\x1b[31;1mDoctest failure:\nExpected: \x1b[32;7m%s\x1b[0m\n\x1b[31;1m But got: \x1b[31;7m%s\x1b[0m\n"
+                            : "Doctest failure:\nExpected: %s\n But got: %s\n",
+                            expected, expr_str);
             }
         }
     }
diff --git a/builtins/functions.h b/builtins/functions.h
index bb8b563..6342c47 100644
--- a/builtins/functions.h
+++ b/builtins/functions.h
@@ -9,8 +9,9 @@
 extern const char *SSS_HASH_VECTOR;
 
 void fail(CORD fmt, ...);
+void fail_source(const char *filename, int64_t start, int64_t end, CORD fmt, ...);
 CORD builtin_last_err();
-void __doctest(void *expr, TypeInfo *type, CORD expected, const char *filename, int start, int end);
+public void __doctest(void *expr, TypeInfo *type, CORD expected, const char *filename, int64_t start, int64_t end);
 
 uint32_t generic_hash(const void *obj, const TypeInfo *type);
 int32_t generic_compare(const void *x, const void *y, const TypeInfo *type);
diff --git a/builtins/table.h b/builtins/table.h
index 69d0aad..d11a876 100644
--- a/builtins/table.h
+++ b/builtins/table.h
@@ -18,10 +18,11 @@
     $table.fallback = fb; \
     $table.default_value = def; \
     $table; })
-#define $Table_get(table_expr, key_t, val_t, key_expr, info_expr) ({ \
+#define $Table_get(table_expr, key_t, val_t, key_expr, info_expr, filename, start, end) ({ \
     const table_t *$t = table_expr; key_t $k = key_expr; const TypeInfo* $info = info_expr; \
     const val_t *$v = Table_get($t, &$k, $info); \
-    if (__builtin_expect($v == NULL, 0)) fail("The key %r is not in this table\n", generic_as_str(&$k, USE_COLOR, $info->TableInfo.key)); \
+    if (__builtin_expect($v == NULL, 0)) \
+        fail_source(filename, start, end, "The key %r is not in this table\n", generic_as_str(&$k, USE_COLOR, $info->TableInfo.key)); \
     *$v; })
 
 
diff --git a/compile.c b/compile.c
index 6b38a9b..a0e613a 100644
--- a/compile.c
+++ b/compile.c
@@ -771,8 +771,14 @@ CORD compile(env_t *env, ast_t *ast)
             type_t *item_type = Match(container_t, ArrayType)->item_type;
             CORD arr = compile_to_pointer_depth(env, indexing->indexed, 1);
             CORD index = compile(env, indexing->index);
-            return CORD_all(indexing->unchecked ? "$Array_get_unchecked" : "$Array_get(",
-                            compile_type(item_type), ", ", arr, ", ", index, ")");
+            file_t *f = indexing->index->file;
+            if (indexing->unchecked)
+                return CORD_all("$Array_get_unchecked", compile_type(item_type), ", ", arr, ", ", index, ")");
+            else
+                return CORD_all("$Array_get(", compile_type(item_type), ", ", arr, ", ", index, ", ",
+                                Str__quoted(f->filename, false), ", ", CORD_asprintf("%ld", (int64_t)(indexing->index->start - f->text)), ", ",
+                                CORD_asprintf("%ld", (int64_t)(indexing->index->end - f->text)),
+                                ")");
         }
         case TableType: {
             type_t *key_t = Match(container_t, TableType)->key_type;
@@ -781,8 +787,12 @@ CORD compile(env_t *env, ast_t *ast)
                 code_err(indexing->index, "This value has type %T, but this table can only be index with keys of type %T", index_t, key_t);
             CORD table = compile_to_pointer_depth(env, indexing->indexed, 1);
             CORD key = compile(env, indexing->index);
+            file_t *f = indexing->index->file;
             return CORD_all("$Table_get(", table, ", ", compile_type(key_t), ", ", compile_type(value_t), ", ",
-                            key, ", ", compile_type_info(env, container_t), ")");
+                            key, ", ", compile_type_info(env, container_t), ", ",
+                            Str__quoted(f->filename, false), ", ", CORD_asprintf("%ld", (int64_t)(indexing->index->start - f->text)), ", ",
+                            CORD_asprintf("%ld", (int64_t)(indexing->index->end - f->text)),
+                            ")");
         }
         default: code_err(ast, "Indexing is not supported for type: %T", container_t);
         }