diff --git a/libyara/modules/magic/magic.c b/libyara/modules/magic/magic.c
index 6e59ddde..124ed2af 100644
--- a/libyara/modules/magic/magic.c
+++ b/libyara/modules/magic/magic.c
@@ -111,8 +111,10 @@ define_function(magic_mime_type)
     {
       magic_setflags(cache->magic_cookie, MAGIC_MIME_TYPE);
 
-      cache->cached_mime_type = yr_strdup(
-          magic_buffer(cache->magic_cookie, block_data, block->size));
+      const char* type = magic_buffer(
+          cache->magic_cookie, block_data, block->size);
+
+      cache->cached_mime_type = (type == NULL) ? NULL : yr_strdup(type);
     }
   }
 
@@ -148,8 +150,10 @@ define_function(magic_type)
     {
       magic_setflags(cache->magic_cookie, 0);
 
-      cache->cached_type = yr_strdup(
-          magic_buffer(cache->magic_cookie, block_data, block->size));
+      const char* type = magic_buffer(
+          cache->magic_cookie, block_data, block->size);
+
+      cache->cached_type = (type == NULL) ? NULL : yr_strdup(type);
     }
   }