diff --git a/goo/gmem.cc b/goo/gmem.cc
index af3e19e..26e1868 100644
--- a/goo/gmem.cc
+++ b/goo/gmem.cc
@@ -330,7 +330,7 @@ void gMemReport(FILE *f) {
 }
 #endif
 
-char *copyString(char *s) {
+char *copyString(const char *s) {
   char *s1;
 
   s1 = (char *)gmalloc(strlen(s) + 1);
diff --git a/goo/gmem.h b/goo/gmem.h
index 0c16b01..b85b40a 100644
--- a/goo/gmem.h
+++ b/goo/gmem.h
@@ -94,7 +94,7 @@ extern void gMemReport(FILE *f);
 /*
  * Allocate memory and copy a string into it.
  */
-extern char *copyString(char *s);
+extern char *copyString(const char *s);
 
 /*
  * Allocate memory and copy a limited-length string to it.
diff --git a/poppler/NameToCharCode.cc b/poppler/NameToCharCode.cc
index efe1c4d..5448dc4 100644
--- a/poppler/NameToCharCode.cc
+++ b/poppler/NameToCharCode.cc
@@ -47,7 +47,7 @@ NameToCharCode::~NameToCharCode() {
   gfree(tab);
 }
 
-void NameToCharCode::add(char *name, CharCode c) {
+void NameToCharCode::add(const char *name, CharCode c) {
   NameToCharCodeEntry *oldTab;
   int h, i, oldSize;
 
@@ -89,7 +89,7 @@ void NameToCharCode::add(char *name, CharCode c) {
   ++len;
 }
 
-CharCode NameToCharCode::lookup(char *name) {
+CharCode NameToCharCode::lookup(const char *name) {
   int h;
 
   h = hash(name);
@@ -104,8 +104,8 @@ CharCode NameToCharCode::lookup(char *name) {
   return 0;
 }
 
-int NameToCharCode::hash(char *name) {
-  char *p;
+int NameToCharCode::hash(const char *name) {
+  const char *p;
   unsigned int h;
 
   h = 0;
diff --git a/poppler/NameToCharCode.h b/poppler/NameToCharCode.h
index bc57c37..5b1092b 100644
--- a/poppler/NameToCharCode.h
+++ b/poppler/NameToCharCode.h
@@ -25,12 +25,12 @@ public:
   NameToCharCode();
   ~NameToCharCode();
 
-  void add(char *name, CharCode c);
-  CharCode lookup(char *name);
+  void add(const char *name, CharCode c);
+  CharCode lookup(const char *name);
 
 private:
 
-  int hash(char *name);
+  int hash(const char *name);
 
   NameToCharCodeEntry *tab;
   int size;
diff --git a/poppler/NameToUnicodeTable.h b/poppler/NameToUnicodeTable.h
index 0b1812c..3ed0247 100644
--- a/poppler/NameToUnicodeTable.h
+++ b/poppler/NameToUnicodeTable.h
@@ -8,7 +8,7 @@
 
 static struct {
   Unicode u;
-  char *name;
+  const char *name;
 } nameToUnicodeTab[] = {
   {0x0021, "!"},
   {0x0023, "#"},