diff --git a/dlls/commdlg/printdlg.h b/dlls/commdlg/printdlg.h
index b554aec34da..c85316b21a4 100644
--- a/dlls/commdlg/printdlg.h
+++ b/dlls/commdlg/printdlg.h
@@ -64,8 +64,8 @@ typedef struct
 
 /* Debugging info */
 static struct pd_flags {
-  DWORD flag;
-  LPSTR name;
+  DWORD  flag;
+  LPCSTR name;
 } pd_flags[] = {
   {PD_SELECTION, "PD_SELECTION "},
   {PD_PAGENUMS, "PD_PAGENUMS "},
diff --git a/dlls/commdlg/printdlg16.c b/dlls/commdlg/printdlg16.c
index 83b7f97bd0b..8f9b70be5ba 100644
--- a/dlls/commdlg/printdlg16.c
+++ b/dlls/commdlg/printdlg16.c
@@ -212,7 +212,7 @@ static LRESULT PRINTDLG_WMInitDialog16(HWND hDlg, WPARAM wParam,
  *      Generates a 16 bits template from the Wine 32 bits resource
  *
  */
-static HGLOBAL16 PRINTDLG_Get16TemplateFrom32(char *PrintResourceName)
+static HGLOBAL16 PRINTDLG_Get16TemplateFrom32(LPCSTR PrintResourceName)
 {
 	HRSRC hResInfo;
 	HGLOBAL hDlgTmpl32;
diff --git a/dlls/ntdll/tests/error.c b/dlls/ntdll/tests/error.c
index cb818078d91..6955653d25d 100644
--- a/dlls/ntdll/tests/error.c
+++ b/dlls/ntdll/tests/error.c
@@ -66,7 +66,7 @@ static int prepare_test(void)
     return 1;
 }
 
-static void cmp_call(NTSTATUS win_nt, ULONG win32, char* message)
+static void cmp_call(NTSTATUS win_nt, ULONG win32, const char* message)
 {
     ULONG err;
 
@@ -76,7 +76,7 @@ static void cmp_call(NTSTATUS win_nt, ULONG win32, char* message)
             message, win_nt, err, win32);
 }
 
-static void cmp_call2(NTSTATUS win_nt, ULONG win32, char* message)
+static void cmp_call2(NTSTATUS win_nt, ULONG win32, const char* message)
 {
     ULONG err;
 
@@ -87,7 +87,7 @@ static void cmp_call2(NTSTATUS win_nt, ULONG win32, char* message)
        message, win_nt, err, win32);
 }
 
-static void cmp_call3(NTSTATUS win_nt, ULONG win32_1, ULONG win32_2, char* message)
+static void cmp_call3(NTSTATUS win_nt, ULONG win32_1, ULONG win32_2, const char* message)
 {
     ULONG err;
 
@@ -97,7 +97,7 @@ static void cmp_call3(NTSTATUS win_nt, ULONG win32_1, ULONG win32_2, char* messa
             message, win_nt, err, win32_1, win32_2);
 }
 
-static void cmp_call4(NTSTATUS win_nt, ULONG win32_1, ULONG win32_2, char* message)
+static void cmp_call4(NTSTATUS win_nt, ULONG win32_1, ULONG win32_2, const char* message)
 {
     ULONG err;
 
diff --git a/dlls/ntdll/tests/large_int.c b/dlls/ntdll/tests/large_int.c
index 2320d578cd5..cf4d219b75b 100644
--- a/dlls/ntdll/tests/large_int.c
+++ b/dlls/ntdll/tests/large_int.c
@@ -133,7 +133,7 @@ typedef struct {
     ULONGLONG value;
     USHORT Length;
     USHORT MaximumLength;
-    char *Buffer;
+    const char *Buffer;
     NTSTATUS result;
 } largeint2str_t;
 
diff --git a/dlls/ntdll/tests/rtlstr.c b/dlls/ntdll/tests/rtlstr.c
index 1f4cb251688..26f3117a5e8 100644
--- a/dlls/ntdll/tests/rtlstr.c
+++ b/dlls/ntdll/tests/rtlstr.c
@@ -87,7 +87,7 @@ static NTSTATUS (WINAPI *pRtlValidateUnicodeString)(long, UNICODE_STRING *);
 /*static DWORD (WINAPI *pRtlIsTextUnicode)(LPVOID, DWORD, DWORD *);*/
 
 
-static WCHAR* AtoW( char* p )
+static WCHAR* AtoW( const char* p )
 {
     WCHAR* buffer;
     DWORD len = MultiByteToWideChar( CP_ACP, 0, p, -1, NULL, 0 );
@@ -296,15 +296,15 @@ typedef struct {
     int source_Length;
     int source_MaximumLength;
     int source_buf_size;
-    char *source_buf;
+    const char *source_buf;
     int dest_Length;
     int dest_MaximumLength;
     int dest_buf_size;
-    char *dest_buf;
+    const char *dest_buf;
     int res_Length;
     int res_MaximumLength;
     int res_buf_size;
-    char *res_buf;
+    const char *res_buf;
     NTSTATUS result;
 } dupl_ustr_t;
 
@@ -714,16 +714,16 @@ typedef struct {
     int ansi_Length;
     int ansi_MaximumLength;
     int ansi_buf_size;
-    char *ansi_buf;
+    const char *ansi_buf;
     int uni_Length;
     int uni_MaximumLength;
     int uni_buf_size;
-    char *uni_buf;
+    const char *uni_buf;
     BOOLEAN doalloc;
     int res_Length;
     int res_MaximumLength;
     int res_buf_size;
-    char *res_buf;
+    const char *res_buf;
     NTSTATUS result;
 } ustr2astr_t;
 
@@ -797,12 +797,12 @@ typedef struct {
     int dest_Length;
     int dest_MaximumLength;
     int dest_buf_size;
-    char *dest_buf;
-    char *src;
+    const char *dest_buf;
+    const char *src;
     int res_Length;
     int res_MaximumLength;
     int res_buf_size;
-    char *res_buf;
+    const char *res_buf;
     NTSTATUS result;
 } app_asc2str_t;
 
@@ -864,15 +864,15 @@ typedef struct {
     int dest_Length;
     int dest_MaximumLength;
     int dest_buf_size;
-    char *dest_buf;
+    const char *dest_buf;
     int src_Length;
     int src_MaximumLength;
     int src_buf_size;
-    char *src_buf;
+    const char *src_buf;
     int res_Length;
     int res_MaximumLength;
     int res_buf_size;
-    char *res_buf;
+    const char *res_buf;
     NTSTATUS result;
 } app_str2str_t;
 
@@ -945,12 +945,12 @@ typedef struct {
     int dest_Length;
     int dest_MaximumLength;
     int dest_buf_size;
-    char *dest_buf;
-    char *src;
+    const char *dest_buf;
+    const char *src;
     int res_Length;
     int res_MaximumLength;
     int res_buf_size;
-    char *res_buf;
+    const char *res_buf;
     NTSTATUS result;
 } app_uni2str_t;
 
@@ -1017,15 +1017,15 @@ typedef struct {
     int dest_Length;
     int dest_MaximumLength;
     int dest_buf_size;
-    char *dest_buf;
+    const char *dest_buf;
     int src_Length;
     int src_MaximumLength;
     int src_buf_size;
-    char *src_buf;
+    const char *src_buf;
     int res_Length;
     int res_MaximumLength;
     int res_buf_size;
-    char *res_buf;
+    const char *res_buf;
     NTSTATUS result;
 } app_ustr2str_t;
 
@@ -1100,8 +1100,8 @@ static void test_RtlAppendUnicodeStringToString(void)
 
 typedef struct {
     int flags;
-    char *main_str;
-    char *search_chars;
+    const char *main_str;
+    const char *search_chars;
     USHORT pos;
     NTSTATUS result;
 } find_ch_in_ustr_t;
@@ -1436,7 +1436,7 @@ typedef struct {
     ULONG value;
     USHORT Length;
     USHORT MaximumLength;
-    char *Buffer;
+    const char *Buffer;
     NTSTATUS result;
 } int2str_t;
 
diff --git a/dlls/ntdll/tests/string.c b/dlls/ntdll/tests/string.c
index 55e48fb2dbd..922999c2d5f 100644
--- a/dlls/ntdll/tests/string.c
+++ b/dlls/ntdll/tests/string.c
@@ -101,7 +101,7 @@ static void InitFunctionPtrs()
 typedef struct {
     int base;
     ULONG value;
-    char *Buffer;
+    const char *Buffer;
     int mask; /* ntdll/msvcrt: 0x01=itoa, 0x02=ltoa, 0x04=ultoa */
               /*               0x10=itow, 0x20=ltow, 0x40=ultow */
 } ulong2str_t;
@@ -442,7 +442,7 @@ static void test_ulongtow(void)
 typedef struct {
     int base;
     ULONGLONG value;
-    char *Buffer;
+    const char *Buffer;
     int mask; /* ntdll/msvcrt: 0x01=i64toa, 0x02=ui64toa, 0x04=wrong _i64toa try next example */
               /*               0x10=i64tow, 0x20=ui64tow, 0x40=wrong _i64tow try next example */
 } ulonglong2str_t;
@@ -773,7 +773,7 @@ static void test_ulonglongtow(void)
 
 
 typedef struct {
-    char *str;
+    const char *str;
     LONG value;
 } str2long_t;
 
@@ -918,7 +918,7 @@ static void test_wtol(void)
 
 
 typedef struct {
-    char *str;
+    const char *str;
     LONGLONG value;
 } str2longlong_t;
 
diff --git a/dlls/opengl32/opengl_ext.h b/dlls/opengl32/opengl_ext.h
index 32e81a24adc..eb8b84fab90 100644
--- a/dlls/opengl32/opengl_ext.h
+++ b/dlls/opengl32/opengl_ext.h
@@ -51,8 +51,8 @@ extern void (*wine_tsx11_unlock_ptr)(void);
 
 
 typedef struct {
-  char  *name;     /* name of the extension */
-  char  *glx_name; /* name used on Unix's libGL */
+  const char  *name;     /* name of the extension */
+  const char  *glx_name; /* name used on Unix's libGL */
   void  *func;     /* pointer to the Wine function for this extension */
   void **func_ptr; /* where to store the value of glXGetProcAddressARB */
 } OpenGL_extension;
diff --git a/dlls/winmm/mciavi/wnd.c b/dlls/winmm/mciavi/wnd.c
index 9cb74ff0dc0..76fa196a813 100644
--- a/dlls/winmm/mciavi/wnd.c
+++ b/dlls/winmm/mciavi/wnd.c
@@ -164,7 +164,7 @@ DWORD	MCIAVI_mciPut(UINT wDevID, DWORD dwFlags, LPMCI_DGV_PUT_PARMS lpParms)
 DWORD	MCIAVI_mciWhere(UINT wDevID, DWORD dwFlags, LPMCI_DGV_RECT_PARMS lpParms)
 {
     WINE_MCIAVI*	wma = MCIAVI_mciGetOpenDev(wDevID);
-    LPSTR		x = "";
+    LPCSTR		x = "";
 
     TRACE("(%04x, %08lx, %p)\n", wDevID, dwFlags, lpParms);