diff --git a/asm/main.c b/asm/main.c
index 563e331..346bebb 100644
--- a/asm/main.c
+++ b/asm/main.c
@@ -6,53 +6,27 @@
 #include "str.h"
 #include <assert.h>
 #include <errno.h>
+#include <libgen.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
-static inline int define_labels(
-    IdentResolver* resolver, PLabel* label, uint16_t asm_ip, Reporter* rep)
-{
-    if (label == NULL)
-        return 0;
-    int res = define_labels(resolver, label->next, asm_ip, rep);
-    const IdentResol* existing = ident_resolver_resolve(resolver, label->ident);
-    if (existing != NULL) {
-        REPORTF_ERROR("redefinition of identifier '%s'", label->ident);
-        reporter_print_loc(rep, label->loc);
-        REPORTF_INFO("original definition of '%s'", label->ident);
-        reporter_print_loc(rep, existing->loc);
-        return 1;
-    }
-    if (label->sub_label) {
-        ident_resolver_define_sublabel(
-            resolver, asm_strdup(label->ident), label->loc, asm_ip);
-    } else {
-        ident_resolver_define_label(
-            resolver, asm_strdup(label->ident), label->loc, asm_ip);
-    }
-    return res;
-}
-
-static inline void use_labels(IdentResolver* resolver, PLabel* label)
-{
-    if (label == NULL)
-        return;
-    use_labels(resolver, label->next);
-    const IdentResol* existing = ident_resolver_resolve(resolver, label->ident);
-    if (existing->ty == IdentResolTy_Label) {
-        resolver->current_parent = existing;
-    }
-}
-
 typedef struct {
     const char* input_file;
     const char* output_file;
 } Args;
 
 static inline Args parse_args(int argc, char** argv);
+static inline char* read_text_file(const char* filename);
+static inline int include_file(IdentResolver* resolver,
+    OperandEvaluator* evaluator,
+    const char* origin,
+    const char* filename);
+static inline int define_labels(
+    IdentResolver* resolver, PLabel* label, uint16_t asm_ip, Reporter* rep);
+static inline void use_labels(IdentResolver* resolver, PLabel* label);
 
 int main(int argc, char** argv)
 {
@@ -60,26 +34,7 @@ int main(int argc, char** argv)
 
     Args args = parse_args(argc, argv);
 
-    FILE* input_fp = fopen(args.input_file, "r");
-    if (!input_fp) {
-        REPORTF_ERROR("could not open input file '%s': %s",
-            args.input_file,
-            strerror(errno));
-        return -1;
-    }
-    fseek(input_fp, 0L, SEEK_END);
-    size_t file_size = (size_t)ftell(input_fp);
-    rewind(input_fp);
-
-    char* input_text = calloc(file_size + 1, sizeof(char));
-    size_t bytes_read = fread(input_text, sizeof(char), file_size, input_fp);
-    fclose(input_fp);
-    if (bytes_read != file_size) {
-        REPORTF_ERROR("could not read input file '%s': %s",
-            args.input_file,
-            strerror(errno));
-        return -1;
-    }
+    char* input_text = read_text_file(args.input_file);
 
     bool errors_occured = false;
 
@@ -132,6 +87,7 @@ int main(int argc, char** argv)
                 if (existing != NULL) {
                     REPORTF_ERROR("redefinition of constant '%s'", stmt->ident);
                     reporter_print_loc(&rep, stmt->loc);
+                    errors_occured = true;
                     pstmt_free(stmt);
                     continue;
                 }
@@ -139,13 +95,26 @@ int main(int argc, char** argv)
                     = eval_operand_to_imm(&evaluator, stmt->value);
                 if (evaled.ty == EoTy_Err) {
                     pstmt_free(stmt);
+                    errors_occured = true;
                     continue;
                 }
-                ident_resolver_define_const(
-                    &resolver, asm_strdup(stmt->ident), stmt->loc, evaled.imm);
+                ident_resolver_define_const(&resolver,
+                    asm_strdup(stmt->ident),
+                    stmt->loc,
+                    evaled.imm,
+                    asm_strdup(args.input_file));
                 pstmt_free(stmt);
                 break;
             }
+            case PStmtTy_Include: {
+                int include_res = include_file(
+                    &resolver, &evaluator, args.input_file, stmt->str);
+                pstmt_free(stmt);
+                if (include_res != 0) {
+                    errors_occured = true;
+                }
+                break;
+            }
         }
     }
 
@@ -257,3 +226,153 @@ static inline Args parse_args(int argc, char** argv)
         output_file,
     };
 }
+
+static inline int include_file(IdentResolver* resolver,
+    OperandEvaluator* evaluator,
+    const char* origin_filename,
+    const char* include_filename)
+{
+
+    char* origin_dir_buf = asm_strdup(origin_filename);
+    const char* origin_dir = dirname(origin_dir_buf);
+
+    char* filepath = calloc(
+        strlen(origin_dir) + strlen(include_filename) + 2, sizeof(char));
+
+    strcat(filepath, origin_dir);
+    free(origin_dir_buf);
+
+    strcat(filepath, "/");
+    strcat(filepath, include_filename);
+
+    char* text = read_text_file(filepath);
+    if (!text)
+        return -1;
+
+    Parser parser;
+    parser_construct(&parser, filepath, text);
+
+    Reporter rep = {
+        .filename = parser.lexer.filename,
+        .text = parser.lexer.text,
+        .text_len = parser.lexer.text_len,
+    };
+
+    bool errors_occured = false;
+
+    while (!parser_done(&parser)) {
+        PStmt* stmt = parser_next_stmt(&parser);
+        if (!stmt) {
+            continue;
+        }
+        switch (stmt->ty) {
+            case PStmtTy_Const: {
+                const IdentResol* existing
+                    = ident_resolver_resolve(resolver, stmt->ident);
+                if (existing != NULL) {
+                    REPORTF_ERROR("redefinition of constant '%s'", stmt->ident);
+                    reporter_print_loc(&rep, stmt->loc);
+                    errors_occured = true;
+                    pstmt_free(stmt);
+                    continue;
+                }
+                EvaledOperand evaled
+                    = eval_operand_to_imm(evaluator, stmt->value);
+                if (evaled.ty == EoTy_Err) {
+                    pstmt_free(stmt);
+                    errors_occured = true;
+                    continue;
+                }
+                ident_resolver_define_const(resolver,
+                    asm_strdup(stmt->ident),
+                    stmt->loc,
+                    evaled.imm,
+                    asm_strdup(filepath));
+                break;
+            }
+            case PStmtTy_Include: {
+                int include_res
+                    = include_file(resolver, evaluator, filepath, stmt->str);
+                pstmt_free(stmt);
+                if (include_res != 0) {
+                    errors_occured = true;
+                }
+                break;
+            }
+            default:
+                break;
+        }
+        pstmt_free(stmt);
+    }
+
+    errors_occured &= parser_error_occured(&parser);
+
+    free(filepath);
+    free(text);
+    return errors_occured;
+}
+
+static inline char* read_text_file(const char* filename)
+{
+    FILE* fp = fopen(filename, "r");
+    if (!fp) {
+        REPORTF_ERROR("could not open file '%s' for reading: %s",
+            filename,
+            strerror(errno));
+        return NULL;
+    }
+    fseek(fp, 0L, SEEK_END);
+    size_t file_size = (size_t)ftell(fp);
+    rewind(fp);
+
+    char* text = calloc(file_size + 1, sizeof(char));
+    size_t bytes_read = fread(text, sizeof(char), file_size, fp);
+    fclose(fp);
+    if (bytes_read != file_size) {
+        REPORTF_ERROR(
+            "could not read input file '%s': %s", filename, strerror(errno));
+        return NULL;
+    }
+    return text;
+}
+
+static inline int define_labels(
+    IdentResolver* resolver, PLabel* label, uint16_t asm_ip, Reporter* rep)
+{
+    if (label == NULL)
+        return 0;
+    int res = define_labels(resolver, label->next, asm_ip, rep);
+    const IdentResol* existing = ident_resolver_resolve(resolver, label->ident);
+    if (existing != NULL) {
+        REPORTF_ERROR("redefinition of identifier '%s'", label->ident);
+        reporter_print_loc(rep, label->loc);
+
+        const char* filename = rep->filename;
+        if (existing->ty == IdentResolTy_Const) {
+            rep->filename = existing->src_filename;
+        }
+        REPORTF_INFO("original definition of '%s'", existing->ident);
+        reporter_print_loc(rep, existing->loc);
+        rep->filename = filename;
+        return 1;
+    }
+    if (label->sub_label) {
+        ident_resolver_define_sublabel(
+            resolver, asm_strdup(label->ident), label->loc, asm_ip);
+    } else {
+        ident_resolver_define_label(
+            resolver, asm_strdup(label->ident), label->loc, asm_ip);
+    }
+    return res;
+}
+
+static inline void use_labels(IdentResolver* resolver, PLabel* label)
+{
+    if (label == NULL)
+        return;
+    use_labels(resolver, label->next);
+    const IdentResol* existing = ident_resolver_resolve(resolver, label->ident);
+    if (existing->ty == IdentResolTy_Label) {
+        resolver->current_parent = existing;
+    }
+}
diff --git a/asm/parse.c b/asm/parse.c
index 25df574..1ef522b 100644
--- a/asm/parse.c
+++ b/asm/parse.c
@@ -139,6 +139,7 @@ PStmt* pstmt_new_ident(PStmtTy ty, Loc loc, char* ident)
     *stmt = (PStmt) { .ty = ty, .loc = loc, .ident = ident, .value = NULL };
     return stmt;
 }
+
 PStmt* pstmt_new_const(PStmtTy ty, Loc loc, char* ident, POperand* value)
 {
     PStmt* stmt = malloc(sizeof(PStmt));
@@ -146,6 +147,13 @@ PStmt* pstmt_new_const(PStmtTy ty, Loc loc, char* ident, POperand* value)
     return stmt;
 }
 
+PStmt* pstmt_new_include(Loc loc, char* str)
+{
+    PStmt* stmt = malloc(sizeof(PStmt));
+    *stmt = (PStmt) { .ty = PStmtTy_Include, .loc = loc, .str = str };
+    return stmt;
+}
+
 void pstmt_free(PStmt* stmt)
 {
     switch (stmt->ty) {
@@ -160,6 +168,9 @@ void pstmt_free(PStmt* stmt)
             free(stmt->ident);
             poperand_free(stmt->value);
             break;
+        case PStmtTy_Include:
+            free(stmt->str);
+            break;
     }
     free(stmt);
 }
@@ -212,6 +223,38 @@ static inline char* parser_text_val(const Parser* parser, Tok tok)
     return asm_strndup(&parser->lexer.text[tok.loc.idx], tok.len);
 }
 
+static inline char literal_char_val(const char* str)
+{
+    if (str[0] == '\\') {
+        switch (str[1]) {
+            case '0':
+                return 0;
+            case 't':
+                return '\t';
+            case 'n':
+                return '\n';
+            default:
+                return str[1];
+        }
+    } else {
+        return str[0];
+    }
+}
+
+static inline char* parser_str_val(
+    const Parser* parser, size_t* str_len, Tok tok)
+{
+    char* lit = parser_text_val(parser, tok);
+    char* str = calloc(tok.len - 1, sizeof(char));
+    *str_len = 0;
+    for (size_t i = 1; i < tok.len - 1; ++i) {
+        str[*str_len] = literal_char_val(&lit[i]);
+        *str_len += 1;
+    }
+    free(lit);
+    return str;
+}
+
 static inline void parser_report(Parser* parser, const char* msg, Loc loc)
 {
     parser->error_occured = true;
@@ -267,24 +310,6 @@ static inline PLabel* parser_parse_labels(
     return labels;
 }
 
-static inline char literal_char_val(const char* str)
-{
-    if (str[0] == '\\') {
-        switch (str[1]) {
-            case '0':
-                return 0;
-            case 't':
-                return '\t';
-            case 'n':
-                return '\n';
-            default:
-                return str[1];
-        }
-    } else {
-        return str[0];
-    }
-}
-
 static const int parser_binary_prec = 6;
 static inline POperand* parser_parse_operand_2(Parser* parser, int prec);
 
@@ -346,14 +371,8 @@ static inline POperand* parser_parse_operand_0(Parser* parser)
         free(str);
         return poperand_new_imm(imm, loc);
     } else if (parser_eat(parser, TT_Str)) {
-        char* lit = parser_text_val(parser, parser->eaten);
-        size_t lit_len = strlen(lit);
-        char* str = calloc(lit_len - 1, sizeof(char));
-        size_t str_len = 0;
-        for (size_t i = 1; i < lit_len - 2; ++i) {
-            str[i] = literal_char_val(&lit[i]);
-        }
-        free(lit);
+        size_t str_len;
+        char* str = parser_str_val(parser, &str_len, parser->eaten);
         return poperand_new_str(PoTy_Str, str, str_len, loc);
     } else if (parser_eat(parser, '.')) {
         if (!parser_eat(parser, TT_Ident)) {
@@ -559,11 +578,13 @@ static inline PStmtTy pstmt_keyword_ty(const char* ident)
         PStmtTy_Global,
         PStmtTy_Extern,
         PStmtTy_Const,
+        PStmtTy_Include,
     };
     const char* keywords[] = {
         "global",
         "extern",
         "const",
+        "include",
     };
     static_assert(
         sizeof(keywords) / sizeof(keywords[0]) == sizeof(tys) / sizeof(tys[0]),
@@ -608,6 +629,17 @@ PStmt* parser_next_stmt(Parser* parser)
             return pstmt_new_const(ty, loc, ident, value);
             break;
         }
+        case PStmtTy_Include: {
+            parser_step(parser);
+            if (!parser_eat(parser, TT_Str)) {
+                parser_report(parser, "expected string", parser->tok.loc);
+                return NULL;
+            }
+            size_t str_len;
+            char* str = parser_str_val(parser, &str_len, parser->eaten);
+            return pstmt_new_include(loc, str);
+            break;
+        }
         default:
             break;
     }
diff --git a/asm/parse.h b/asm/parse.h
index 21de608..048e6fb 100644
--- a/asm/parse.h
+++ b/asm/parse.h
@@ -85,6 +85,7 @@ typedef enum {
     PStmtTy_Global,
     PStmtTy_Extern,
     PStmtTy_Const,
+    PStmtTy_Include,
 } PStmtTy;
 
 typedef struct {
@@ -96,12 +97,14 @@ typedef struct {
             char* ident;
             POperand* value;
         };
+        char* str;
     };
 } PStmt;
 
 PStmt* pstmt_new_line(Loc loc, PLine* line);
 PStmt* pstmt_new_ident(PStmtTy ty, Loc loc, char* ident);
 PStmt* pstmt_new_const(PStmtTy ty, Loc loc, char* ident, POperand* value);
+PStmt* pstmt_new_include(Loc loc, char* str);
 void pstmt_free(PStmt* stmt);
 
 typedef struct {
diff --git a/asm/resolve.c b/asm/resolve.c
index eba9489..ee65c0f 100644
--- a/asm/resolve.c
+++ b/asm/resolve.c
@@ -9,8 +9,11 @@ void ident_resol_destroy(IdentResol* resol)
             break;
         case IdentResolTy_Label:
         case IdentResolTy_SubLabel:
+            free(resol->ident);
+            break;
         case IdentResolTy_Const:
             free(resol->ident);
+            free(resol->src_filename);
             break;
     }
 }
@@ -78,8 +81,11 @@ void ident_resolver_define_sublabel(
     };
 }
 
-void ident_resolver_define_const(
-    IdentResolver* resolver, char* ident, Loc loc, uint16_t value)
+void ident_resolver_define_const(IdentResolver* resolver,
+    char* ident,
+    Loc loc,
+    uint16_t value,
+    char* src_filename)
 {
     size_t i = ident_resolver_first_empty(resolver);
     resolver->resols[i] = (IdentResol) {
@@ -87,6 +93,7 @@ void ident_resolver_define_const(
         .loc = loc,
         .ty = IdentResolTy_Const,
         .value = value,
+        .src_filename = src_filename,
     };
 }
 
diff --git a/asm/resolve.h b/asm/resolve.h
index d31be46..ef40472 100644
--- a/asm/resolve.h
+++ b/asm/resolve.h
@@ -18,7 +18,10 @@ struct IdentResol {
     IdentResolTy ty;
     union {
         uint16_t ip;
-        uint16_t value;
+        struct {
+            uint16_t value;
+            char* src_filename;
+        };
     };
 };
 
@@ -38,7 +41,10 @@ void ident_resolver_define_label(
     IdentResolver* resolver, char* ident, Loc loc, uint16_t asm_ip);
 void ident_resolver_define_sublabel(
     IdentResolver* resolver, char* ident, Loc loc, uint16_t asm_ip);
-void ident_resolver_define_const(
-    IdentResolver* resolver, char* ident, Loc loc, uint16_t value);
+void ident_resolver_define_const(IdentResolver* resolver,
+    char* ident,
+    Loc loc,
+    uint16_t value,
+    char* src_filename);
 const IdentResol* ident_resolver_resolve(
     const IdentResolver* resolver, const char* ident);
diff --git a/kern/arch.asm b/kern/arch.asm
new file mode 100644
index 0000000..df6ea16
--- /dev/null
+++ b/kern/arch.asm
@@ -0,0 +1,26 @@
+
+const Fl_Zero 0
+const Fl_Eq 1
+const Fl_Be 2
+const Fl_Lt 3
+const Fl_Err 4
+const Fl_Int 5
+const Fl_Vcd 6
+
+const Int_DiskRead 0
+const Int_DiskWrite 1
+const Int_Key 32
+
+const Device_Keyboard 0
+
+const vcd_ch_width 8
+const vcd_ch_height 8
+const vcd_width_in_ch 40
+const vcd_height_in_ch 12
+
+const vcd_px_width 4
+const vcd_px_height 8
+const vcd_width_in_px vcd_width_in_ch * vcd_ch_width * vcd_px_width
+const vcd_height_in_px vcd_height_in_ch * vcd_ch_height * vcd_px_height
+
+; vim: syntax=nasm
diff --git a/kern/main.asm b/kern/main.asm
index aa27796..d3e8807 100644
--- a/kern/main.asm
+++ b/kern/main.asm
@@ -1,27 +1,5 @@
 
-const Fl_Zero 0
-const Fl_Eq 1
-const Fl_Be 2
-const Fl_Lt 3
-const Fl_Err 4
-const Fl_Int 5
-const Fl_Vcd 6
-
-const Int_DiskRead 0
-const Int_DiskWrite 1
-const Int_Key 32
-
-const Device_Keyboard 0
-
-const vcd_ch_width 8
-const vcd_ch_height 8
-const vcd_width_in_ch 40
-const vcd_height_in_ch 12
-
-const vcd_px_width 4
-const vcd_px_height 8
-const vcd_width_in_px vcd_width_in_ch * vcd_ch_width * vcd_px_width
-const vcd_height_in_px vcd_height_in_ch * vcd_ch_height * vcd_px_height
+include "arch.asm"
 
 start:
     ; rsp points *at* the top element