diff --git a/src/util/cmatrix.c b/src/util/cmatrix.c
index 3d93b9fed..f42980c55 100644
--- a/src/util/cmatrix.c
+++ b/src/util/cmatrix.c
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: cmatrix.c,v 2.28 2020/03/30 20:41:47 greg Exp $";
+static const char RCSid[] = "$Id: cmatrix.c,v 2.29 2021/01/15 02:46:28 greg Exp $";
 #endif
 /*
  * Color matrix routines.
@@ -33,7 +33,7 @@ cm_alloc(int nrows, int ncols)
 	if ((nrows <= 0) | (ncols <= 0))
 		error(USER, "attempt to create empty matrix");
 	cm = (CMATRIX *)malloc(sizeof(CMATRIX) +
-				sizeof(COLOR)*(nrows*ncols - 1));
+				sizeof(COLOR)*((size_t)nrows*ncols - 1));
 	if (!cm)
 		error(SYSTEM, "out of memory in cm_alloc()");
 	cm->nrows = nrows;
diff --git a/src/util/rmatrix.c b/src/util/rmatrix.c
index 1c379bc71..0d76fe8ee 100644
--- a/src/util/rmatrix.c
+++ b/src/util/rmatrix.c
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: rmatrix.c,v 2.44 2020/05/07 18:45:16 greg Exp $";
+static const char RCSid[] = "$Id: rmatrix.c,v 2.45 2021/01/15 02:46:28 greg Exp $";
 #endif
 /*
  * General matrix operations.
@@ -24,7 +24,7 @@ rmx_alloc(int nr, int nc, int n)
 	if ((nr <= 0) | (nc <= 0) | (n <= 0))
 		return(NULL);
 	dnew = (RMATRIX *)malloc(sizeof(RMATRIX)-sizeof(dnew->mtx) +
-					sizeof(dnew->mtx[0])*(n*nr*nc));
+					sizeof(dnew->mtx[0])*n*nr*nc);
 	if (!dnew)
 		return(NULL);
 	dnew->nrows = nr; dnew->ncols = nc; dnew->ncomp = n;