diff --git a/src/osgPlugins/zip/unzip.cpp b/src/osgPlugins/zip/unzip.cpp
index 73cae9fb4..108f99630 100644
--- a/src/osgPlugins/zip/unzip.cpp
+++ b/src/osgPlugins/zip/unzip.cpp
@@ -1809,18 +1809,18 @@ uInt *v)               // working area: values in order of bit length
   uInt f;                       // i repeats in table every f entries
   int g;                        // maximum code length
   int h;                        // table level
-  register uInt i;              // counter, current code
-  register uInt j;              // counter
-  register int k;               // number of bits in current code
+  uInt i;                       // counter, current code
+  uInt j;                       // counter
+  int k;                        // number of bits in current code
   int l;                        // bits per table (returned in m)
   uInt mask;                    // (1 << w) - 1, to avoid cc -O bug on HP
-  register uInt *p;            // pointer into c[], b[], or v[]
+  uInt *p;                      // pointer into c[], b[], or v[]
   inflate_huft *q;              // points to current table
   struct inflate_huft_s r;      // table entry for structure assignment
   inflate_huft *u[BMAX];        // table stack
-  register int w;               // bits before this table == (l * h)
+  int w;                        // bits before this table == (l * h)
   uInt x[BMAX+1];               // bit offsets, then code stack
-  uInt *xp;                    // pointer into x
+  uInt *xp;                     // pointer into x
   int y;                        // number of dummy codes added
   uInt z;                       // number of entries in current table