diff --git a/src/plugins/e-acsl/share/e-acsl/e_acsl_bits.h b/src/plugins/e-acsl/share/e-acsl/e_acsl_bits.h
index 20000bb62a465c5a8e02aa2a64ece103b7a10fea..436433f27de5fdadfa34a840a032c1beb857d89a 100644
--- a/src/plugins/e-acsl/share/e-acsl/e_acsl_bits.h
+++ b/src/plugins/e-acsl/share/e-acsl/e_acsl_bits.h
@@ -36,6 +36,7 @@
 #define E_ACSL_BITS
 
 #include <stdint.h>
+#include <stddef.h>
 
 /* Check if we have little-endian and abort the execution otherwise. */
 #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__