diff --git a/src/globals.c b/src/globals.c
index a0c09933..f6107e41 100644
--- a/src/globals.c
+++ b/src/globals.c
@@ -911,7 +911,7 @@ void add_insn(block_t *block,
     bb->insn_list.tail = n;
 }
 
-source_t *create_source(int init_capacity)
+source_t *source_create(int init_capacity)
 {
     source_t *array = malloc(sizeof(source_t));
     if (!array)
@@ -928,12 +928,18 @@ source_t *create_source(int init_capacity)
     return array;
 }
 
-bool source_expand(source_t *src)
+bool source_extend(source_t *src, int len)
 {
-    if (src->size < src->capacity)
+    int new_size = src->size + len;
+
+    if (new_size < src->capacity)
         return true;
 
-    src->capacity <<= 1;
+    if (new_size > src->capacity << 1)
+        src->capacity = new_size;
+    else
+        src->capacity <<= 1;
+
     char *new_arr = malloc(src->capacity * sizeof(char));
 
     if (!new_arr)
@@ -949,7 +955,7 @@ bool source_expand(source_t *src)
 
 bool source_push(source_t *src, char value)
 {
-    if (!source_expand(src))
+    if (!source_extend(src, 1))
         return false;
 
     src->elements[src->size] = value;
@@ -958,7 +964,20 @@ bool source_push(source_t *src, char value)
     return true;
 }
 
-void source_release(source_t *src)
+bool source_push_str(source_t *src, char *value)
+{
+    int len = strlen(value);
+
+    if (!source_extend(src, len))
+        return false;
+
+    strncpy(src->elements + src->size, value, len);
+    src->size += len;
+
+    return true;
+}
+
+void source_free(source_t *src)
 {
     if (!src)
         return;
@@ -985,7 +1004,7 @@ void global_init()
     BB_ARENA = arena_init(DEFAULT_ARENA_SIZE);
     PH2_IR_FLATTEN = malloc(MAX_IR_INSTR * sizeof(ph2_ir_t *));
     LABEL_LUT = malloc(MAX_LABEL * sizeof(label_lut_t));
-    SOURCE = create_source(MAX_SOURCE);
+    SOURCE = source_create(MAX_SOURCE);
     INCLUSION_MAP = hashmap_create(MAX_INCLUSIONS);
     ALIASES = malloc(MAX_ALIASES * sizeof(alias_t));
     CONSTANTS = malloc(MAX_CONSTANTS * sizeof(constant_t));
@@ -1018,7 +1037,7 @@ void global_release()
     arena_free(BB_ARENA);
     free(PH2_IR_FLATTEN);
     free(LABEL_LUT);
-    source_release(SOURCE);
+    source_free(SOURCE);
     hashmap_free(INCLUSION_MAP);
     free(ALIASES);
     free(CONSTANTS);
diff --git a/src/parser.c b/src/parser.c
index d70913e7..661c13b9 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -3428,8 +3428,7 @@ void load_source_file(char *file)
             snprintf(path + c + 1, inclusion_path_len, "%s", buffer + 10);
             load_source_file(path);
         } else {
-            strcpy(SOURCE->elements + SOURCE->size, buffer);
-            SOURCE->size += strlen(buffer);
+            source_push_str(SOURCE, buffer);
         }
     }
 
diff --git a/tools/inliner.c b/tools/inliner.c
index 952c412c..56cf7be1 100644
--- a/tools/inliner.c
+++ b/tools/inliner.c
@@ -12,24 +12,98 @@
  * C runtime and essential libraries.
  */
 
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 #define MAX_LINE_LEN 200
-#define MAX_SIZE 65536
+#define DEFAULT_SOURCE_SIZE 65536
 
-char *SOURCE;
-int source_idx;
+#define write_char(c) source_push(SOURCE, c)
+#define write_str(s) source_push_str(SOURCE, s)
 
-void write_char(char c)
+typedef struct {
+    int size;
+    int capacity;
+    char *elements;
+} source_t;
+
+source_t *SOURCE;
+
+source_t *source_create(int init_capacity)
+{
+    source_t *array = malloc(sizeof(source_t));
+    if (!array)
+        return NULL;
+
+    array->size = 0;
+    array->capacity = init_capacity;
+    array->elements = malloc(array->capacity * sizeof(char));
+    if (!array->elements) {
+        free(array);
+        return NULL;
+    }
+
+    return array;
+}
+
+bool source_extend(source_t *src, int len)
+{
+    int new_size = src->size + len;
+
+    if (new_size < src->capacity)
+        return true;
+
+    if (new_size > src->capacity << 1)
+        src->capacity = new_size;
+    else
+        src->capacity <<= 1;
+
+    char *new_arr = malloc(src->capacity * sizeof(char));
+
+    if (!new_arr)
+        return false;
+
+    memcpy(new_arr, src->elements, src->size * sizeof(char));
+
+    free(src->elements);
+    src->elements = new_arr;
+
+    return true;
+}
+
+bool source_push(source_t *src, char value)
 {
-    SOURCE[source_idx++] = c;
+    if (!source_extend(src, 1))
+        return false;
+
+    src->elements[src->size] = value;
+    src->size++;
+
+    return true;
 }
 
-void write_str(char *str)
+bool source_push_str(source_t *src, char *value)
 {
-    for (int i = 0; str[i]; i++)
-        write_char(str[i]);
+    int len = strlen(value);
+
+    if (!source_extend(src, len))
+        return false;
+
+    strncpy(src->elements + src->size, value, len);
+    src->size += len;
+
+    return true;
+}
+
+void source_free(source_t *src)
+{
+    if (!src)
+        return;
+
+    free(src->elements);
+    free(src);
 }
 
 void write_line(char *src)
@@ -66,8 +140,8 @@ void load_from(char *file)
 void save_to(char *file)
 {
     FILE *f = fopen(file, "wb");
-    for (int i = 0; i < source_idx; i++)
-        fputc(SOURCE[i], f);
+    for (int i = 0; i < SOURCE->size; i++)
+        fputc(SOURCE->elements[i], f);
     fclose(f);
 }
 
@@ -78,8 +152,7 @@ int main(int argc, char *argv[])
         return -1;
     }
 
-    source_idx = 0;
-    SOURCE = malloc(MAX_SIZE);
+    SOURCE = source_create(DEFAULT_SOURCE_SIZE);
 
     write_str("/* Created by tools/inliner - DO NOT EDIT. */\n");
 
@@ -94,14 +167,14 @@ int main(int argc, char *argv[])
      *   __c("}\n");
      */
     write_str("void __c(char *src) {\n");
-    write_str("    for (int i = 0; src[i]; i++)\n");
-    write_str("        source_push(SOURCE, src[i]);\n");
+    write_str("    source_push_str(SOURCE, src);\n");
     write_str("}\n");
 
     write_str("void libc_generate() {\n");
     load_from(argv[1]);
     write_str("}\n");
     save_to(argv[2]);
+    source_free(SOURCE);
 
     return 0;
 }