diff --git a/library/ecp_curves.c b/library/ecp_curves.c
index ee211af..6dd7ed3 100644
--- a/library/ecp_curves.c
+++ b/library/ecp_curves.c
@@ -4976,7 +4976,7 @@
 
 #define MAX32       X_limbs
 #define A(j)        X[j]
-#define STORE32     X[i] = cur;
+#define STORE32     X[i] = (mbedtls_mpi_uint) cur;
 #define STORE0      X[i] = 0;
 
 #else /* 64 bit */