diff --git a/libbacktrace/BacktraceMap.cpp b/libbacktrace/BacktraceMap.cpp
index ba86632..19551dc 100644
--- a/libbacktrace/BacktraceMap.cpp
+++ b/libbacktrace/BacktraceMap.cpp
@@ -15,6 +15,7 @@
  */
 
 #include <ctype.h>
+#include <inttypes.h>
 #include <stdint.h>
 #include <sys/types.h>
 #include <unistd.h>
@@ -46,8 +47,8 @@
 }
 
 bool BacktraceMap::ParseLine(const char* line, backtrace_map_t* map) {
-  unsigned long int start;
-  unsigned long int end;
+  uint64_t start;
+  uint64_t end;
   char permissions[5];
   int name_pos;
 
@@ -56,14 +57,14 @@
 // __TEXT                 0009f000-000a1000 [    8K     8K] r-x/rwx SM=COW  /Volumes/android/dalvik-dev/out/host/darwin-x86/bin/libcorkscrew_test\n
 // 012345678901234567890123456789012345678901234567890123456789
 // 0         1         2         3         4         5
-  if (sscanf(line, "%*21c %lx-%lx [%*13c] %3c/%*3c SM=%*3c  %n",
+  if (sscanf(line, "%*21c %" SCNx64 "-%" SCNx64 " [%*13c] %3c/%*3c SM=%*3c  %n",
              &start, &end, permissions, &name_pos) != 3) {
 #else
 // Linux /proc/<pid>/maps lines:
 // 6f000000-6f01e000 rwxp 00000000 00:0c 16389419   /system/lib/libcomposer.so\n
 // 012345678901234567890123456789012345678901234567890123456789
 // 0         1         2         3         4         5
-  if (sscanf(line, "%lx-%lx %4s %*x %*x:%*x %*d %n",
+  if (sscanf(line, "%" SCNx64 "-%" SCNx64 " %4s %*x %*x:%*x %*d %n",
              &start, &end, permissions, &name_pos) != 3) {
 #endif
     return false;
diff --git a/libbacktrace/GetPss.cpp b/libbacktrace/GetPss.cpp
index 09a721d..b4dc48d 100644
--- a/libbacktrace/GetPss.cpp
+++ b/libbacktrace/GetPss.cpp
@@ -33,7 +33,7 @@
 #define PAGEMAP_SWAP_OFFSET(x) (_BITS(x, 5, 50))
 #define PAGEMAP_SWAP_TYPE(x)   (_BITS(x, 0,  5))
 
-static bool ReadData(int fd, unsigned long place, uint64_t *data) {
+static bool ReadData(int fd, off_t place, uint64_t *data) {
   if (lseek(fd, place * sizeof(uint64_t), SEEK_SET) < 0) {
     return false;
   }
@@ -71,12 +71,13 @@
       total_pss = 0;
       break;
     }
-    for (size_t page = start/pagesize; page < end/pagesize; page++) {
+    for (off_t page = static_cast<off_t>(start/pagesize);
+         page < static_cast<off_t>(end/pagesize); page++) {
       uint64_t data;
       if (ReadData(pagemap_fd, page, &data)) {
         if (PAGEMAP_PRESENT(data) && !PAGEMAP_SWAPPED(data)) {
           uint64_t count;
-          if (ReadData(pagecount_fd, PAGEMAP_PFN(data), &count)) {
+          if (ReadData(pagecount_fd, static_cast<off_t>(PAGEMAP_PFN(data)), &count)) {
             total_pss += (count >= 1) ? pagesize / count : 0;
           }
         }