diff --git a/include/mbedtls/padlock.h b/include/mbedtls/padlock.h
index 0cc52bd..aace4d3 100644
--- a/include/mbedtls/padlock.h
+++ b/include/mbedtls/padlock.h
@@ -37,7 +37,7 @@
 
 /* Some versions of ASan result in errors about not enough registers */
 #if defined(MBEDTLS_HAVE_ASM) && defined(__GNUC__) && defined(__i386__) && \
-    defined(MBEDTLS_HAVE_ASAN)
+    !defined(MBEDTLS_HAVE_ASAN)
 
 #ifndef MBEDTLS_HAVE_X86
 #define MBEDTLS_HAVE_X86