diff --git a/README.md b/README.md
index abfd1cd4db..7f0a72f5df 100644
--- a/README.md
+++ b/README.md
@@ -55,7 +55,7 @@ To install NCCL on the system, create a package then install it as root.
 Debian/Ubuntu :
 ```shell
 $ # Install tools to create debian packages
-$ sudo apt install build-essential devscripts debhelper
+$ sudo apt install build-essential devscripts debhelper fakeroot
 $ # Build NCCL deb package
 $ make pkg.debian.build
 $ ls build/pkg/deb/
diff --git a/src/init.cc b/src/init.cc
index 42499c0313..0158f8ddff 100644
--- a/src/init.cc
+++ b/src/init.cc
@@ -880,10 +880,12 @@ static ncclResult_t getCpuGpuAffinity(int cudaDev, cpu_set_t* mask) {
   path[PATH_MAX-1] = '\0';
   int fd;
   SYSCHECKVAL(open(path, O_RDONLY), "open", fd);
-  char affinityStr[sizeof(cpu_set_t)*2];
+  char affinityStr[sizeof(cpu_set_t)*2 + 1];
   int r = read(fd, affinityStr, sizeof(cpu_set_t)*2);
-  if (r > 0)
+  if (r > 0) {
+    affinityStr[r] = '\0';
     NCCLCHECK(ncclStrToCpuset(affinityStr, mask));
+  }
   close(fd);
   free(cudaPath);
   return ncclSuccess;