diff --git a/libyara/modules/dex/dex.c b/libyara/modules/dex/dex.c
index f850d20a7b..a1efdd0a8a 100644
--- a/libyara/modules/dex/dex.c
+++ b/libyara/modules/dex/dex.c
@@ -492,19 +492,13 @@ dex_header_t* dex_get_header(const uint8_t* data, size_t data_size)
 void dex_parse_header(dex_header_t* dex_header, YR_OBJECT* module_object)
 {
   yr_set_sized_string(
-      (char*) dex_header->magic,
-      strnlen((char*) dex_header->magic, 8 * sizeof(char)),
-      module_object,
-      "header.magic");
+      (char*) dex_header->magic, 8, module_object, "header.magic");
 
   yr_set_integer(
       yr_le32toh(dex_header->checksum), module_object, "header.checksum");
 
   yr_set_sized_string(
-      (char*) dex_header->signature,
-      strnlen((char*) dex_header->signature, 20 * sizeof(char)),
-      module_object,
-      "header.signature");
+      (char*) dex_header->signature, 20, module_object, "header.signature");
 
   yr_set_integer(
       yr_le32toh(dex_header->file_size), module_object, "header.file_size");
@@ -1461,11 +1455,16 @@ int module_load(
 
   dex_header_t* dex_header;
 
-  yr_set_string(DEX_FILE_MAGIC_035, module_object, "DEX_FILE_MAGIC_035");
-  yr_set_string(DEX_FILE_MAGIC_036, module_object, "DEX_FILE_MAGIC_036");
-  yr_set_string(DEX_FILE_MAGIC_037, module_object, "DEX_FILE_MAGIC_037");
-  yr_set_string(DEX_FILE_MAGIC_038, module_object, "DEX_FILE_MAGIC_038");
-  yr_set_string(DEX_FILE_MAGIC_039, module_object, "DEX_FILE_MAGIC_039");
+  yr_set_sized_string(
+      DEX_FILE_MAGIC_035, 8, module_object, "DEX_FILE_MAGIC_035");
+  yr_set_sized_string(
+      DEX_FILE_MAGIC_036, 8, module_object, "DEX_FILE_MAGIC_036");
+  yr_set_sized_string(
+      DEX_FILE_MAGIC_037, 8, module_object, "DEX_FILE_MAGIC_037");
+  yr_set_sized_string(
+      DEX_FILE_MAGIC_038, 8, module_object, "DEX_FILE_MAGIC_038");
+  yr_set_sized_string(
+      DEX_FILE_MAGIC_039, 8, module_object, "DEX_FILE_MAGIC_039");
 
   yr_set_integer(0x12345678, module_object, "ENDIAN_CONSTANT");
   yr_set_integer(0x78563412, module_object, "REVERSE_ENDIAN_CONSTANT");