diff --git a/include/pocketpy/common/vector.h b/include/pocketpy/common/vector.h
index 93f784f4..1716e645 100644
--- a/include/pocketpy/common/vector.h
+++ b/include/pocketpy/common/vector.h
@@ -23,6 +23,7 @@ void* c11_vector__emplace(c11_vector* self);
 bool c11_vector__contains(const c11_vector* self, void* elem);
 void* c11_vector__submit(c11_vector* self, int* length);
 void c11_vector__swap(c11_vector* self, c11_vector* other);
+int c11_vector__nextcap(c11_vector* self);
 
 #define c11__getitem(T, self, index) (((T*)(self)->data)[index])
 #define c11__setitem(T, self, index, value) ((T*)(self)->data)[index] = value;
@@ -30,7 +31,9 @@ void c11_vector__swap(c11_vector* self, c11_vector* other);
 
 #define c11_vector__push(T, self, elem)                                                            \
     do {                                                                                           \
-        if((self)->length == (self)->capacity) c11_vector__reserve((self), (self)->capacity * 2);  \
+        if((self)->length == (self)->capacity) {                                                   \
+            c11_vector__reserve((self), c11_vector__nextcap((self)));                              \
+        }                                                                                          \
         ((T*)(self)->data)[(self)->length] = (elem);                                               \
         (self)->length++;                                                                          \
     } while(0)
@@ -42,15 +45,19 @@ void c11_vector__swap(c11_vector* self, c11_vector* other);
 #define c11_vector__extend(T, self, p, size)                                                       \
     do {                                                                                           \
         int min_capacity = (self)->length + (size);                                                \
-        if((self)->capacity < min_capacity)                                                        \
-            c11_vector__reserve((self), c11__max((self)->capacity * 2, min_capacity));             \
+        if((self)->capacity < min_capacity) {                                                      \
+            int nextcap = c11_vector__nextcap(self);                                               \
+            c11_vector__reserve((self), c11__max(nextcap, min_capacity));                          \
+        }                                                                                          \
         memcpy((T*)(self)->data + (self)->length, (p), (size) * sizeof(T));                        \
         (self)->length += (size);                                                                  \
     } while(0)
 
 #define c11_vector__insert(T, self, index, elem)                                                   \
     do {                                                                                           \
-        if((self)->length == (self)->capacity) c11_vector__reserve((self), (self)->capacity * 2);  \
+        if((self)->length == (self)->capacity) {                                                   \
+            c11_vector__reserve((self), c11_vector__nextcap(self));                                \
+        }                                                                                          \
         T* p = (T*)(self)->data + (index);                                                         \
         memmove(p + 1, p, ((self)->length - (index)) * sizeof(T));                                 \
         *p = (elem);                                                                               \
diff --git a/src/common/vector.c b/src/common/vector.c
index 32b97fe4..af767262 100644
--- a/src/common/vector.c
+++ b/src/common/vector.c
@@ -40,7 +40,7 @@ void c11_vector__reserve(c11_vector* self, int capacity) {
 void c11_vector__clear(c11_vector* self) { self->length = 0; }
 
 void* c11_vector__emplace(c11_vector* self) {
-    if(self->length == self->capacity) c11_vector__reserve(self, self->capacity * 2);
+    if(self->length == self->capacity) { c11_vector__reserve(self, c11_vector__nextcap(self)); }
     void* p = (char*)self->data + (size_t)self->elem_size * (size_t)self->length;
     self->length++;
     return p;
@@ -63,8 +63,17 @@ void* c11_vector__submit(c11_vector* self, int* length) {
     return retval;
 }
 
-void c11_vector__swap(c11_vector *self, c11_vector *other){
+void c11_vector__swap(c11_vector* self, c11_vector* other) {
     c11_vector tmp = *self;
     *self = *other;
     *other = tmp;
 }
+
+int c11_vector__nextcap(c11_vector* self) {
+    if(self->capacity < 1024) {
+        return self->capacity * 2;
+    } else {
+        // increase by 25%
+        return self->capacity + (self->capacity >> 2);
+    }
+}
\ No newline at end of file