diff --git a/include/hydroforth/interpreter.h b/include/hydroforth/interpreter.h
index 44c0c76..6cb37e8 100644
--- a/include/hydroforth/interpreter.h
+++ b/include/hydroforth/interpreter.h
@@ -17,10 +17,13 @@ struct hf__interpreter__word {
 
 extern const hf__hashmap__free_value_t hf__interpreter__word_free;
 
+#define HF__INTERPRETER__CALL_STACK_CAP_MAX 1024
+
 struct hf__interpreter {
   struct hf__node *call_stack;
   size_t call_stack_len;
-  size_t call_stack_size;
+  size_t call_stack_cap;
+  size_t call_stack_cap_max;
 
   struct hf__hashmap words; // struct hf__interpreter__word *
 
@@ -41,7 +44,7 @@ extern const hf__interpreter__word_func_t
     HF__INTERPRETER__WORD_FUNCTION[__HF__NODE_TYPE__N];
 
 extern void hf__interpreter__stack_push(long **arr, size_t *const len,
-                                        size_t *const size, long item);
+                                        size_t *const cap, long item);
 
 extern struct hf__result
 hf__interpreter__run(struct hf__interpreter *const interpreter);
diff --git a/include/hydroforth/lexer.h b/include/hydroforth/lexer.h
index 51b1481..ee1293f 100644
--- a/include/hydroforth/lexer.h
+++ b/include/hydroforth/lexer.h
@@ -24,6 +24,6 @@ struct hf__token {
 
 extern void hf__lex(const char *const src, const size_t src_len,
                     struct hf__token **tokens, size_t *const len,
-                    size_t *const size);
+                    size_t *const cap);
 
 #endif
\ No newline at end of file
diff --git a/include/hydroforth/parser.h b/include/hydroforth/parser.h
index 0dc93dd..7aa2b4c 100644
--- a/include/hydroforth/parser.h
+++ b/include/hydroforth/parser.h
@@ -74,12 +74,12 @@ extern void hf__parser__init_keyword_map(struct hf__hashmap *const map,
                                          size_t cap);
 
 extern void hf__parser__node_array_push(struct hf__node **arr,
-                                        size_t *const len, size_t *const size,
+                                        size_t *const len, size_t *const cap,
                                         struct hf__node item);
 
 extern struct hf__result
 hf__parse(struct hf__parser *const parser, const char *const src,
           const struct hf__token *const tokens, const size_t tokens_len,
-          struct hf__node **nodes, size_t *const len, size_t *const size);
+          struct hf__node **nodes, size_t *const len, size_t *const cap);
 
 #endif
diff --git a/include/hydroforth/result.h b/include/hydroforth/result.h
index 3d12ba2..cad7475 100644
--- a/include/hydroforth/result.h
+++ b/include/hydroforth/result.h
@@ -9,6 +9,7 @@ enum hf__error {
   HF__ERROR__PARSER__WORD_DEF_INVALID_NAME,
   HF__ERROR__PARSER__WORD_DEF_IS_KEYWORD,
 
+  HF__ERROR__INTERPRETER__CALL_STACK_TOO_BIG,
   HF__ERROR__INTERPRETER__UNKNOWN_WORD,
   HF__ERROR__INTERPRETER__WORD_ALREADY_DEF,
   HF__ERROR__INTERPRETER__STACK_UNDERFLOW,
@@ -31,12 +32,27 @@ static const char *const HF__ERROR_STR[__HF__ERROR__N] = {
         "Invalid token type for word name",
     [HF__ERROR__PARSER__WORD_DEF_IS_KEYWORD] = "Word name is already a keyword",
 
+    [HF__ERROR__INTERPRETER__CALL_STACK_TOO_BIG] = "Call stack is too big",
     [HF__ERROR__INTERPRETER__UNKNOWN_WORD] = "Unknown word",
     [HF__ERROR__INTERPRETER__WORD_ALREADY_DEF] = "Word is already defined",
     [HF__ERROR__INTERPRETER__STACK_UNDERFLOW] = "Stack underflow",
 };
 
-extern void hf__print_error(struct hf__error_wrapper *error);
+static const bool HF__ERROR_PANIC[__HF__ERROR__N] = {
+    [HF__ERROR__PARSER__UNEXPECTED] = false,
+    [HF__ERROR__PARSER__INVALID_NUMBER] = false,
+    [HF__ERROR__PARSER__INVALID_CHAR] = false,
+    [HF__ERROR__PARSER__WORD_DEF_INCOMPLETE] = false,
+    [HF__ERROR__PARSER__WORD_DEF_INVALID_NAME] = false,
+    [HF__ERROR__PARSER__WORD_DEF_IS_KEYWORD] = false,
+
+    [HF__ERROR__INTERPRETER__CALL_STACK_TOO_BIG] = true,
+    [HF__ERROR__INTERPRETER__UNKNOWN_WORD] = false,
+    [HF__ERROR__INTERPRETER__WORD_ALREADY_DEF] = false,
+    [HF__ERROR__INTERPRETER__STACK_UNDERFLOW] = false,
+};
+
+extern void hf__handle_error_light(struct hf__error_wrapper *error);
 
 struct hf__result {
   bool ok;
diff --git a/src/hydroforth/interpreter.c b/src/hydroforth/interpreter.c
index 2941a8d..1f4d876 100644
--- a/src/hydroforth/interpreter.c
+++ b/src/hydroforth/interpreter.c
@@ -56,9 +56,9 @@ struct hf__result words__word(struct hf__interpreter *const interpreter,
   }
 
   for (size_t i = (*word)->body_len - 1; i != 0 - 1; i--) {
-    hf__parser__node_array_push(
-        &interpreter->call_stack, &interpreter->call_stack_len,
-        &interpreter->call_stack_size, (*word)->body[i]);
+    hf__parser__node_array_push(&interpreter->call_stack,
+                                &interpreter->call_stack_len,
+                                &interpreter->call_stack_cap, (*word)->body[i]);
     interpreter->call_stack[interpreter->call_stack_len - 1].is_owner = false;
   }
 
@@ -343,12 +343,12 @@ const hf__interpreter__word_func_t
 };
 
 void hf__interpreter__stack_push(long **arr, size_t *const len,
-                                 size_t *const size, long item) {
-  if (*len > *size) {
+                                 size_t *const cap, long item) {
+  if (*len > *cap) {
     return;
-  } else if (*len == *size) {
-    *size += 1 + (*size / 2);
-    *arr = realloc(*arr, sizeof(long) * (*size));
+  } else if (*len == *cap) {
+    *cap += 1 + (*cap / 2);
+    *arr = realloc(*arr, sizeof(long) * (*cap));
   }
 
   (*arr)[*len] = item;
@@ -363,15 +363,27 @@ hf__interpreter__run(struct hf__interpreter *const interpreter) {
 
   const struct hf__node *const top =
       interpreter->call_stack + --interpreter->call_stack_len;
-  SET_8_VALUE_COLOUR(TXT_RED);
-  printf("--- type = %u ---\n", top->type);
-  if (top->type == HF__NODE_TYPE__WORD) {
-    printf("--- word name = \"%s\"\n", top->value.word.value);
-  }
-  SET_8_VALUE_COLOUR(TXT_DEFAULT);
-
   const hf__interpreter__word_func_t func =
       HF__INTERPRETER__WORD_FUNCTION[top->type];
 
-  return func ? func(interpreter, top) : HF__OK;
+  if (func) {
+    struct hf__result res = func(interpreter, top);
+
+    if (res.ok && interpreter->call_stack_cap_max != 0 &&
+        interpreter->call_stack_cap >= interpreter->call_stack_cap_max) {
+      const size_t required_size =
+          snprintf(NULL, 0, "%lu >= %lu", interpreter->call_stack_cap,
+                   interpreter->call_stack_cap_max);
+      char *msg = malloc(sizeof(char) * (required_size + 1));
+      snprintf(msg, required_size + 1, "%lu >= %lu",
+               interpreter->call_stack_cap, interpreter->call_stack_cap_max);
+
+      return HF__ERR_CUSTOM(HF__ERROR__INTERPRETER__CALL_STACK_TOO_BIG, msg,
+                            true);
+    } else {
+      return res;
+    }
+  } else {
+    return HF__OK;
+  }
 }
diff --git a/src/hydroforth/lexer.c b/src/hydroforth/lexer.c
index 5879883..c939722 100644
--- a/src/hydroforth/lexer.c
+++ b/src/hydroforth/lexer.c
@@ -17,7 +17,7 @@ void token_array_push(struct hf__token **arr, size_t *const len,
 }
 
 void hf__lex(const char *const src, const size_t src_len,
-             struct hf__token **tokens, size_t *const len, size_t *const size) {
+             struct hf__token **tokens, size_t *const len, size_t *const cap) {
   size_t i = 0;
   while (i < src_len) {
     if (hf__is_space_like(src[i]) || src[i] == '\n') {
@@ -28,7 +28,12 @@ void hf__lex(const char *const src, const size_t src_len,
     size_t start = i;
     struct hf__token token;
 
-    if (src[i] == '\'') {
+    while (!hf__is_space_like(src[i]) && src[i] != '\n' && i < src_len) {
+      i++;
+    }
+    const size_t str_len = i - start;
+
+    if (str_len == 1 && src[start] == '\'') {
       const size_t char_start = start;
       i++;
       start = i;
@@ -45,76 +50,69 @@ void hf__lex(const char *const src, const size_t src_len,
       token.location.end = i - 1;
 
       i++;
-    } else {
-      while (!hf__is_space_like(src[i]) && src[i] != '\n' && i < src_len) {
+    } else if (hf__is_numeric(src[start]) ||
+               (src[start] == '-' && str_len > 1 &&
+                hf__is_numeric(src[start + 1]))) {
+      token.type = HF__TOKEN_TYPE__NUMBER;
+      token.location.start = start;
+      token.location.end = i - 1;
+    } else if (str_len == 1 && src[start] == ':') {
+      token.type = HF__TOKEN_TYPE__COLON;
+      token.location.start = start;
+      token.location.end = i - 1;
+    } else if (str_len == 1 && src[start] == ';') {
+      token.type = HF__TOKEN_TYPE__SEMICOLON;
+      token.location.start = start;
+      token.location.end = i - 1;
+    } else if (str_len == 1 && src[start] == '(' && hf__is_space_like(src[i])) {
+      i++;
+      bool got_end = false;
+      while (i < src_len) {
+        if (src[i] == ')' && hf__is_space_like(src[i - 1])) {
+          got_end = true;
+          break;
+        }
         i++;
       }
-      const size_t str_len = i - start;
 
-      if (hf__is_numeric(src[start]) || (src[start] == '-' && str_len > 1 &&
-                                         hf__is_numeric(src[start + 1]))) {
-        token.type = HF__TOKEN_TYPE__NUMBER;
-        token.location.start = start;
-        token.location.end = i - 1;
-      } else if (str_len == 1 && src[start] == ':') {
-        token.type = HF__TOKEN_TYPE__COLON;
-        token.location.start = start;
-        token.location.end = i - 1;
-      } else if (str_len == 1 && src[start] == ';') {
-        token.type = HF__TOKEN_TYPE__SEMICOLON;
-        token.location.start = start;
-        token.location.end = i - 1;
-      } else if (str_len == 1 && src[start] == '(' &&
-                 hf__is_space_like(src[i])) {
+      if (got_end) {
+        token.type = HF__TOKEN_TYPE__PAREN_COMMENT;
+        token.location.start = start + 2;
+        token.location.end = i - 2;
         i++;
-        bool got_end = false;
-        while (i < src_len) {
-          if (src[i] == ')' && hf__is_space_like(src[i - 1])) {
-            got_end = true;
-            break;
-          }
-          i++;
-        }
-
-        if (got_end) {
-          token.type = HF__TOKEN_TYPE__PAREN_COMMENT;
-          token.location.start = start + 2;
-          token.location.end = i - 2;
-          i++;
-        } else {
-          i = start + 1;
-          goto TOKEN_IS_WORD;
-        }
-      } else if (str_len == 1 && src[start] == '\\' &&
-                 hf__is_space_like(src[i])) {
-        token.type = HF__TOKEN_TYPE__BACKSLASH_COMMENT;
-
-        start = ++i;
-        while (src[i] != '\n' && i < src_len) {
-          i++;
-        }
-
-        token.location.start = start;
-        token.location.end = i - 1;
-      } else if (str_len == 2 && strncmp(src + start, "--", 2) == 0 &&
-                 (hf__is_space_like(src[i]) || src[i] == '\0')) {
-        token.type = HF__TOKEN_TYPE__DASH_COMMENT;
-
-        start = ++i;
-        while (src[i] != '\n' && i < src_len) {
-          i++;
-        }
-
-        token.location.start = start;
-        token.location.end = i - 1;
       } else {
-      TOKEN_IS_WORD:
-        token.type = HF__TOKEN_TYPE__WORD;
-        token.location.start = start;
-        token.location.end = i - 1;
+        i = start + 1;
+        goto TOKEN_IS_WORD;
       }
+    } else if (str_len == 1 && src[start] == '\\' &&
+               hf__is_space_like(src[i])) {
+      token.type = HF__TOKEN_TYPE__BACKSLASH_COMMENT;
+
+      start = ++i;
+      while (src[i] != '\n' && i < src_len) {
+        i++;
+      }
+
+      token.location.start = start;
+      token.location.end = i - 1;
+    } else if (str_len == 2 && strncmp(src + start, "--", 2) == 0 &&
+               (hf__is_space_like(src[i]) || src[i] == '\0')) {
+      token.type = HF__TOKEN_TYPE__DASH_COMMENT;
+
+      start = ++i;
+      while (src[i] != '\n' && i < src_len) {
+        i++;
+      }
+
+      token.location.start = start;
+      token.location.end = i - 1;
+    } else {
+    TOKEN_IS_WORD:
+      token.type = HF__TOKEN_TYPE__WORD;
+      token.location.start = start;
+      token.location.end = i - 1;
     }
 
-    token_array_push(tokens, len, size, token);
+    token_array_push(tokens, len, cap, token);
   }
 }
\ No newline at end of file
diff --git a/src/hydroforth/parser.c b/src/hydroforth/parser.c
index ba4df45..6a6498b 100644
--- a/src/hydroforth/parser.c
+++ b/src/hydroforth/parser.c
@@ -21,12 +21,12 @@ void hf__parser__init_keyword_map(struct hf__hashmap *const map, size_t cap) {
 }
 
 void hf__parser__node_array_push(struct hf__node **arr, size_t *const len,
-                                 size_t *const size, struct hf__node item) {
-  if (*len > *size) {
+                                 size_t *const cap, struct hf__node item) {
+  if (*len > *cap) {
     return;
-  } else if (*len == *size) {
-    *size += 1 + (*size / 2);
-    *arr = realloc(*arr, sizeof(struct hf__node) * (*size));
+  } else if (*len == *cap) {
+    *cap += 1 + (*cap / 2);
+    *arr = realloc(*arr, sizeof(struct hf__node) * (*cap));
   }
 
   (*arr)[*len] = item;
diff --git a/src/hydroforth/result.c b/src/hydroforth/result.c
index ffe7440..6f73aeb 100644
--- a/src/hydroforth/result.c
+++ b/src/hydroforth/result.c
@@ -4,7 +4,7 @@
 
 #include "hydroforth/hydroforth.h"
 
-void hf__print_error(struct hf__error_wrapper *error) {
+void hf__handle_error_light(struct hf__error_wrapper *error) {
   SET_8_VALUE_COLOUR(TXT_RED);
   printf("Error: %s", HF__ERROR_STR[error->error]);
 
@@ -23,4 +23,9 @@ void hf__print_error(struct hf__error_wrapper *error) {
   printf("[0x%x]", error->error);
 
   SET_8_VALUE_COLOUR(TXT_DEFAULT);
+
+  if (HF__ERROR_PANIC[error->error]) {
+    putchar('\n');
+    exit(1);
+  }
 }
\ No newline at end of file
diff --git a/src/main.c b/src/main.c
index 1a21c67..d6c2ca1 100644
--- a/src/main.c
+++ b/src/main.c
@@ -107,7 +107,8 @@ struct hf__result shell(const struct arguments *const arguments) {
   struct hf__interpreter interpreter = {
       .call_stack = malloc(sizeof(struct hf__node) * 10),
       .call_stack_len = 0,
-      .call_stack_size = 10,
+      .call_stack_cap = 10,
+      .call_stack_cap_max = HF__INTERPRETER__CALL_STACK_CAP_MAX,
 
       .words =
           {
@@ -148,7 +149,7 @@ struct hf__result shell(const struct arguments *const arguments) {
     free(tokens);
     free(input);
     if (!parse_res.ok) {
-      hf__print_error(&parse_res.error);
+      hf__handle_error_light(&parse_res.error);
       putchar('\n');
       continue;
     }
@@ -156,7 +157,7 @@ struct hf__result shell(const struct arguments *const arguments) {
     for (size_t i = nodes_len - 1; i != 0 - 1; i--) {
       hf__parser__node_array_push(&interpreter.call_stack,
                                   &interpreter.call_stack_len,
-                                  &interpreter.call_stack_size, nodes[i]);
+                                  &interpreter.call_stack_cap, nodes[i]);
     }
     free(nodes);
 
@@ -166,7 +167,7 @@ struct hf__result shell(const struct arguments *const arguments) {
     while (interpreter.call_stack_len != 0 && interpreter.is_running) {
       struct hf__result res = hf__interpreter__run(&interpreter);
       if (!res.ok) {
-        hf__print_error(&res.error);
+        hf__handle_error_light(&res.error);
         putchar('\n');
       }
     }
@@ -229,7 +230,7 @@ int main(int argc, char *argv[]) {
     }
 
     if (!res.ok) {
-      hf__print_error(&res.error);
+      hf__handle_error_light(&res.error);
       putchar('\n');
       return 1;
     }
@@ -256,7 +257,8 @@ int main(int argc, char *argv[]) {
     struct hf__interpreter interpreter = {
         .call_stack = malloc(sizeof(struct hf__node) * 10),
         .call_stack_len = 0,
-        .call_stack_size = 10,
+        .call_stack_cap = 10,
+        .call_stack_cap_max = HF__INTERPRETER__CALL_STACK_CAP_MAX,
 
         .words =
             {
@@ -283,7 +285,7 @@ int main(int argc, char *argv[]) {
     struct hf__result parse_res = hf__parse(&parser, src, tokens, tokens_len,
                                             &nodes, &nodes_len, &nodes_size);
     if (!parse_res.ok) {
-      hf__print_error(&parse_res.error);
+      hf__handle_error_light(&parse_res.error);
       putchar('\n');
       return 1;
     }
@@ -293,7 +295,7 @@ int main(int argc, char *argv[]) {
     for (size_t i = nodes_len - 1; i != 0 - 1; i--) {
       hf__parser__node_array_push(&interpreter.call_stack,
                                   &interpreter.call_stack_len,
-                                  &interpreter.call_stack_size, nodes[i]);
+                                  &interpreter.call_stack_cap, nodes[i]);
     }
     free(nodes);
 
@@ -301,7 +303,7 @@ int main(int argc, char *argv[]) {
     while (interpreter.call_stack_len != 0 && interpreter.is_running) {
       struct hf__result res = hf__interpreter__run(&interpreter);
       if (!res.ok) {
-        hf__print_error(&res.error);
+        hf__handle_error_light(&res.error);
         putchar('\n');
 
         if (arguments.debug) {