diff --git a/prism/extension.c b/prism/extension.c
index 1a471000b49606..292e67891f386b 100644
--- a/prism/extension.c
+++ b/prism/extension.c
@@ -1047,30 +1047,16 @@ integer_parse(VALUE self, VALUE source) {
     pm_integer_t integer = { 0 };
     pm_integer_parse(&integer, PM_INTEGER_BASE_UNKNOWN, start, start + length);
 
-    VALUE number;
-
-    if (integer.values == NULL) {
-        number = UINT2NUM(integer.value);
-    } else {
-        number = UINT2NUM(0);
-        for (size_t i = 0; i < integer.length; i++) {
-            VALUE receiver = rb_funcall(UINT2NUM(integer.values[i]), rb_intern("<<"), 1, ULONG2NUM(i * 32));
-            number = rb_funcall(receiver, rb_intern("|"), 1, number);
-        }
-    }
-
-    if (integer.negative) number = rb_funcall(number, rb_intern("-@"), 0);
-
     pm_buffer_t buffer = { 0 };
     pm_integer_string(&buffer, &integer);
 
     VALUE string = rb_str_new(pm_buffer_value(&buffer), pm_buffer_length(&buffer));
     pm_buffer_free(&buffer);
-    pm_integer_free(&integer);
 
     VALUE result = rb_ary_new_capa(2);
-    rb_ary_push(result, number);
+    rb_ary_push(result, pm_integer_new(&integer));
     rb_ary_push(result, string);
+    pm_integer_free(&integer);
 
     return result;
 }
diff --git a/prism/extension.h b/prism/extension.h
index 6e5a3450122a93..13a9aabde3e5c3 100644
--- a/prism/extension.h
+++ b/prism/extension.h
@@ -10,6 +10,7 @@
 VALUE pm_source_new(const pm_parser_t *parser, rb_encoding *encoding);
 VALUE pm_token_new(const pm_parser_t *parser, const pm_token_t *token, rb_encoding *encoding, VALUE source);
 VALUE pm_ast_new(const pm_parser_t *parser, const pm_node_t *node, rb_encoding *encoding, VALUE source);
+VALUE pm_integer_new(const pm_integer_t *integer);
 
 void Init_prism_api_node(void);
 void Init_prism_pack(void);
diff --git a/prism/templates/ext/prism/api_node.c.erb b/prism/templates/ext/prism/api_node.c.erb
index a195fa6325d7b4..0e8aaae3226093 100644
--- a/prism/templates/ext/prism/api_node.c.erb
+++ b/prism/templates/ext/prism/api_node.c.erb
@@ -37,23 +37,26 @@ pm_string_new(const pm_string_t *string, rb_encoding *encoding) {
     return rb_enc_str_new((const char *) pm_string_source(string), pm_string_length(string), encoding);
 }
 
-static VALUE
+VALUE
 pm_integer_new(const pm_integer_t *integer) {
     VALUE result;
-    if (integer->values) {
-        VALUE str = rb_str_new(NULL, integer->length * 8);
-        unsigned char *buf = (unsigned char *)RSTRING_PTR(str);
+    if (integer->values == NULL) {
+        result = UINT2NUM(integer->value);
+    } else {
+        VALUE string = rb_str_new(NULL, integer->length * 8);
+        unsigned char *bytes = (unsigned char *) RSTRING_PTR(string);
+
         size_t offset = integer->length * 8;
-        for (size_t i = 0; i < integer->length; i++) {
-            uint32_t value = integer->values[i];
-            for (int i = 0; i < 8; i++) {
-                int n = (value >> (4 * i)) & 0xf;
-                buf[--offset] = n < 10 ? n + '0' : n - 10 + 'a';
+        for (size_t value_index = 0; value_index < integer->length; value_index++) {
+            uint32_t value = integer->values[value_index];
+
+            for (int index = 0; index < 8; index++) {
+                int byte = (value >> (4 * index)) & 0xf;
+                bytes[--offset] = byte < 10 ? byte + '0' : byte - 10 + 'a';
             }
         }
-        result = rb_funcall(str, rb_intern("to_i"), 1, UINT2NUM(16));
-    } else {
-        result = UINT2NUM(integer->value);
+
+        result = rb_funcall(string, rb_intern("to_i"), 1, UINT2NUM(16));
     }
 
     if (integer->negative) {
diff --git a/prism/util/pm_integer.c b/prism/util/pm_integer.c
index 1f198af101b858..160a78920c0086 100644
--- a/prism/util/pm_integer.c
+++ b/prism/util/pm_integer.c
@@ -29,8 +29,9 @@ big_add(pm_integer_t *destination, pm_integer_t *left, pm_integer_t *right, uint
 
     size_t length = left_length < right_length ? right_length : left_length;
     uint32_t *values = (uint32_t *) xmalloc(sizeof(uint32_t) * (length + 1));
-    uint64_t carry = 0;
+    if (values == NULL) return;
 
+    uint64_t carry = 0;
     for (size_t index = 0; index < length; index++) {
         uint64_t sum = carry + (index < left_length ? left_values[index] : 0) + (index < right_length ? right_values[index] : 0);
         values[index] = (uint32_t) (sum % base);
@@ -54,36 +55,15 @@ static void
 big_sub2(pm_integer_t *destination, pm_integer_t *a, pm_integer_t *b, pm_integer_t *c, uint64_t base) {
     size_t a_length;
     uint32_t *a_values;
-
-    if (a->values == NULL) {
-        a_length = 1;
-        a_values = &a->value;
-    } else {
-        a_length = a->length;
-        a_values = a->values;
-    }
+    INTEGER_EXTRACT(a, a_length, a_values)
 
     size_t b_length;
     uint32_t *b_values;
-
-    if (b->values == NULL) {
-        b_length = 1;
-        b_values = &b->value;
-    } else {
-        b_length = b->length;
-        b_values = b->values;
-    }
+    INTEGER_EXTRACT(b, b_length, b_values)
 
     size_t c_length;
     uint32_t *c_values;
-
-    if (c->values == NULL) {
-        c_length = 1;
-        c_values = &c->value;
-    } else {
-        c_length = c->length;
-        c_values = c->values;
-    }
+    INTEGER_EXTRACT(c, c_length, c_values)
 
     uint32_t *values = (uint32_t*) xmalloc(sizeof(uint32_t) * a_length);
     int64_t carry = 0;
@@ -137,6 +117,7 @@ karatsuba_multiply(pm_integer_t *destination, pm_integer_t *left, pm_integer_t *
     if (left_length <= 10) {
         size_t length = left_length + right_length;
         uint32_t *values = (uint32_t *) xcalloc(length, sizeof(uint32_t));
+        if (values == NULL) return;
 
         for (size_t left_index = 0; left_index < left_length; left_index++) {
             uint32_t carry = 0;
@@ -293,6 +274,8 @@ pm_integer_from_uint64(pm_integer_t *integer, uint64_t value, uint64_t base) {
     }
 
     uint32_t *values = (uint32_t *) xmalloc(sizeof(uint32_t) * length);
+    if (values == NULL) return;
+
     for (size_t value_index = 0; value_index < length; value_index++) {
         values[value_index] = (uint32_t) (value % base);
         value /= base;
@@ -340,6 +323,7 @@ pm_integer_convert_base(pm_integer_t *destination, const pm_integer_t *source, u
 
     size_t bigints_length = (source_length + 1) / 2;
     pm_integer_t *bigints = (pm_integer_t *) xcalloc(bigints_length, sizeof(pm_integer_t));
+    if (bigints == NULL) return;
 
     for (size_t index = 0; index < source_length; index += 2) {
         uint64_t value = source_values[index] + base_from * (index + 1 < source_length ? source_values[index + 1] : 0);
@@ -516,7 +500,7 @@ pm_integer_parse(pm_integer_t *integer, pm_integer_base_t base, const uint8_t *s
 
     const uint8_t *cursor = start;
     uint64_t value = (uint64_t) pm_integer_parse_digit(*cursor++);
- 
+
     for (; cursor < end; cursor++) {
         if (*cursor == '_') continue;
         value = value * multiplier + (uint64_t) pm_integer_parse_digit(*cursor);
@@ -528,7 +512,7 @@ pm_integer_parse(pm_integer_t *integer, pm_integer_base_t base, const uint8_t *s
             return;
         }
     }
- 
+
     integer->value = (uint32_t) value;
 }