diff --git a/dbms/src/Common/MiAllocator.cpp b/dbms/src/Common/MiAllocator.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..456609374ee8b6838bacfe69fb9710a8b4d70094
--- /dev/null
+++ b/dbms/src/Common/MiAllocator.cpp
@@ -0,0 +1,43 @@
+#include <Common/config.h>
+
+#if USE_MIMALLOC
+
+#include "MiAllocator.h"
+#include <mimalloc.h>
+
+namespace DB
+{
+
+void * MiAllocator::alloc(size_t size, size_t alignment)
+{
+    if (alignment == 0)
+        return mi_malloc(size);
+    else
+        return mi_malloc_aligned(size, alignment);
+}
+
+void MiAllocator::free(void * buf, size_t)
+{
+    mi_free(buf);
+}
+
+void * MiAllocator::realloc(void * old_ptr, size_t, size_t new_size, size_t alignment)
+{
+    if (old_ptr == nullptr)
+        return alloc(new_size, alignment);
+
+    if (new_size == 0)
+    {
+        mi_free(old_ptr);
+        return nullptr;
+    }
+
+    if (alignment == 0)
+        return mi_realloc(old_ptr, alignment);
+
+    return mi_realloc_aligned(old_ptr, new_size, alignment);
+}
+
+}
+
+#endif
diff --git a/dbms/src/Common/MiAllocator.h b/dbms/src/Common/MiAllocator.h
index 075328e5d94fe5178666cca9ca4eb236222a4014..48cfc6f9ab4db4fd8ce6171feda57a81d2d6e075 100644
--- a/dbms/src/Common/MiAllocator.h
+++ b/dbms/src/Common/MiAllocator.h
@@ -6,7 +6,6 @@
 #error "do not include this file until USE_MIMALLOC is set to 1"
 #endif
 
-#include <mimalloc.h>
 #include <cstddef>
 
 namespace DB
@@ -19,37 +18,11 @@ namespace DB
  */
 struct MiAllocator
 {
+    static void * alloc(size_t size, size_t alignment = 0);
 
-    static void * alloc(size_t size, size_t alignment = 0)
-    {
-        if (alignment == 0)
-            return mi_malloc(size);
-        else
-            return mi_malloc_aligned(size, alignment);
-    }
-
-    static void free(void * buf, size_t)
-    {
-        mi_free(buf);
-    }
-
-    static void * realloc(void * old_ptr, size_t, size_t new_size, size_t alignment = 0)
-    {
-        if (old_ptr == nullptr)
-            return alloc(new_size, alignment);
-
-        if (new_size == 0)
-        {
-            mi_free(old_ptr);
-            return nullptr;
-        }
-
-        if (alignment == 0)
-            return mi_realloc(old_ptr, alignment);
-
-        return mi_realloc_aligned(old_ptr, new_size, alignment);
-    }
+    static void free(void * buf, size_t);
 
+    static void * realloc(void * old_ptr, size_t, size_t new_size, size_t alignment = 0);
 };
 
 }