diff --git a/libbacktrace/GetPss.cpp b/libbacktrace/GetPss.cpp
index b4dc48d..6d750ea 100644
--- a/libbacktrace/GetPss.cpp
+++ b/libbacktrace/GetPss.cpp
@@ -24,7 +24,7 @@
 
 // This is an extremely simplified version of libpagemap.
 
-#define _BITS(x, offset, bits) (((x) >> offset) & ((1LL << (bits)) - 1))
+#define _BITS(x, offset, bits) (((x) >> (offset)) & ((1LL << (bits)) - 1))
 
 #define PAGEMAP_PRESENT(x)     (_BITS(x, 63, 1))
 #define PAGEMAP_SWAPPED(x)     (_BITS(x, 62, 1))
diff --git a/libbacktrace/backtrace_test.cpp b/libbacktrace/backtrace_test.cpp
index df6c6c1..7066c79 100644
--- a/libbacktrace/backtrace_test.cpp
+++ b/libbacktrace/backtrace_test.cpp
@@ -1420,7 +1420,7 @@
 #if defined(ENABLE_PSS_TESTS)
 #include "GetPss.h"
 
-#define MAX_LEAK_BYTES 32*1024UL
+#define MAX_LEAK_BYTES (32*1024UL)
 
 void CheckForLeak(pid_t pid, pid_t tid) {
   // Do a few runs to get the PSS stable.