diff --git a/base/src/nsIFileStream.cpp b/base/src/nsIFileStream.cpp
index 13bc8191ab7..c5147fa4770 100644
--- a/base/src/nsIFileStream.cpp
+++ b/base/src/nsIFileStream.cpp
@@ -307,7 +307,7 @@ NS_IMETHODIMP FileImpl::Seek(PRSeekWhence whence, PRInt32 offset)
     PRInt32 position = PR_Seek(mFileDesc, 0, PR_SEEK_CUR);
     PRInt32 available = PR_Available(mFileDesc);
     PRInt32 fileSize = position + available;
-    PRInt32 newPosition;
+    PRInt32 newPosition = 0;
     switch (whence)
     {
         case PR_SEEK_CUR: newPosition = position + offset; break;
diff --git a/dbm/src/hash_buf.c b/dbm/src/hash_buf.c
index b443316bb47..f30bee32efa 100644
--- a/dbm/src/hash_buf.c
+++ b/dbm/src/hash_buf.c
@@ -111,8 +111,8 @@ __get_buf(HTAB *hashp, uint32 addr, BUFHEAD *prev_bp, int newpage)
 {
 	register BUFHEAD *bp;
 	register uint32 is_disk_mask;
-	register int is_disk, segment_ndx;
-	SEGMENT segp;
+	register int is_disk, segment_ndx = 0;
+	SEGMENT segp = 0;
 
 	is_disk = 0;
 	is_disk_mask = 0;
diff --git a/xpcom/io/nsIFileStream.cpp b/xpcom/io/nsIFileStream.cpp
index 13bc8191ab7..c5147fa4770 100644
--- a/xpcom/io/nsIFileStream.cpp
+++ b/xpcom/io/nsIFileStream.cpp
@@ -307,7 +307,7 @@ NS_IMETHODIMP FileImpl::Seek(PRSeekWhence whence, PRInt32 offset)
     PRInt32 position = PR_Seek(mFileDesc, 0, PR_SEEK_CUR);
     PRInt32 available = PR_Available(mFileDesc);
     PRInt32 fileSize = position + available;
-    PRInt32 newPosition;
+    PRInt32 newPosition = 0;
     switch (whence)
     {
         case PR_SEEK_CUR: newPosition = position + offset; break;