diff --git a/src/_types.hpp b/src/_types.hpp
index 6ffda99fb..58f0b2742 100644
--- a/src/_types.hpp
+++ b/src/_types.hpp
@@ -25,10 +25,12 @@ typedef  unsigned long long uint64_t;
 
 typedef  uint32_t Error;
 
-#ifdef _LP64
+#if defined(_LP64) || defined(__ppc64__)
 typedef uint64_t size_t;
-#elif _LP32
+#elif defined(_LP32) || defined(__ppc__)
 typedef uint32_t size_t;
+#else
+#error size_t undefined
 #endif
 
 }
diff --git a/src/filestore.hpp b/src/filestore.hpp
index 196050820..fe3be67fc 100644
--- a/src/filestore.hpp
+++ b/src/filestore.hpp
@@ -187,7 +187,7 @@ FileStore<FsSize_t>::FileStore(uint8_t *begin, uint8_t *end, Error *error): m_ve
 		auto header = (FsHeader*) m_begin;
 		m_root = ptr<Inode*>(header->rootInode);
 		if (error) {
-			*error = header->size != m_end - m_begin;
+			*error = header->size != (unsigned ) (m_end - m_begin);
 		}
 	}
 }