diff --git a/interface/imatcopy.c b/interface/imatcopy.c
index 93ffd69f9..91975f7f4 100644
--- a/interface/imatcopy.c
+++ b/interface/imatcopy.c
@@ -150,9 +150,9 @@ void CNAME( enum CBLAS_ORDER CORDER, enum CBLAS_TRANSPOSE CTRANS, blasint crows,
 #endif
 
 	if ( *lda >  *ldb )
-		msize = (*lda) * (*ldb)  * sizeof(FLOAT);
+		msize = (size_t)(*lda) * (*ldb)  * sizeof(FLOAT);
 	else
-		msize = (*ldb) * (*ldb)  * sizeof(FLOAT);
+		msize = (size_t)(*ldb) * (*ldb)  * sizeof(FLOAT);
 
 	b = malloc(msize);
 	if ( b == NULL )
diff --git a/interface/zimatcopy.c b/interface/zimatcopy.c
index 87964e20d..ecda5ef4e 100644
--- a/interface/zimatcopy.c
+++ b/interface/zimatcopy.c
@@ -172,9 +172,9 @@ void CNAME( enum CBLAS_ORDER CORDER, enum CBLAS_TRANSPOSE CTRANS, blasint crows,
 #endif
 
 	if ( *lda >  *ldb )
-                msize = (*lda) * (*ldb)  * sizeof(FLOAT) * 2;
+                msize = (size_t)(*lda) * (*ldb)  * sizeof(FLOAT) * 2;
         else
-                msize = (*ldb) * (*ldb)  * sizeof(FLOAT) * 2;
+                msize = (size_t)(*ldb) * (*ldb)  * sizeof(FLOAT) * 2;
 
         b = malloc(msize);
         if ( b == NULL )