diff --git a/dlls/gdi32/dibdrv/objects.c b/dlls/gdi32/dibdrv/objects.c
index 5ff9d1a9011..1f05ab050a9 100644
--- a/dlls/gdi32/dibdrv/objects.c
+++ b/dlls/gdi32/dibdrv/objects.c
@@ -1362,7 +1362,7 @@ static void add_join( dibdrv_physdev *pdev, HRGN region, HRGN round_cap, const P
     return;
 }
 
-static int wide_line_segment( dibdrv_physdev *pdev, HRGN total,
+static BOOL wide_line_segment( dibdrv_physdev *pdev, HRGN total,
                                const POINT *pt_1, const POINT *pt_2, int dx, int dy,
                                BOOL need_cap_1, BOOL need_cap_2, struct face *face_1, struct face *face_2 )
 {
@@ -1370,7 +1370,7 @@ static int wide_line_segment( dibdrv_physdev *pdev, HRGN total,
     BOOL sq_cap_1 = need_cap_1 && (pdev->pen_endcap == PS_ENDCAP_SQUARE);
     BOOL sq_cap_2 = need_cap_2 && (pdev->pen_endcap == PS_ENDCAP_SQUARE);
 
-    if (dx == 0 && dy == 0) return 0;
+    if (dx == 0 && dy == 0) return FALSE;
 
     if (dy == 0)
     {
@@ -1487,7 +1487,7 @@ static int wide_line_segment( dibdrv_physdev *pdev, HRGN total,
     face_1->dx = face_2->dx = dx;
     face_1->dy = face_2->dy = dy;
 
-    return 1;
+    return TRUE;
 }
 
 static void wide_line_segments( dibdrv_physdev *pdev, int num, const POINT *pts, BOOL close,
diff --git a/dlls/gdi32/enhmfdrv/objects.c b/dlls/gdi32/enhmfdrv/objects.c
index 4e1f3b16501..60414a3a168 100644
--- a/dlls/gdi32/enhmfdrv/objects.c
+++ b/dlls/gdi32/enhmfdrv/objects.c
@@ -81,7 +81,7 @@ BOOL EMFDRV_DeleteObject( PHYSDEV dev, HGDIOBJ obj )
     UINT index;
     BOOL ret = TRUE;
 
-    if(!(index = EMFDRV_FindObject(dev, obj))) return 0;
+    if(!(index = EMFDRV_FindObject(dev, obj))) return FALSE;
 
     emr.emr.iType = EMR_DELETEOBJECT;
     emr.emr.nSize = sizeof(emr);
diff --git a/dlls/gdi32/metafile.c b/dlls/gdi32/metafile.c
index 406728e0b2e..0cb36afa2de 100644
--- a/dlls/gdi32/metafile.c
+++ b/dlls/gdi32/metafile.c
@@ -471,7 +471,7 @@ BOOL WINAPI EnumMetaFile(HDC hdc, HMETAFILE hmf, MFENUMPROC lpEnumFunc, LPARAM l
 
     TRACE("(%p,%p,%p,%lx)\n", hdc, hmf, lpEnumFunc, lpData);
 
-    if (!mh) return 0;
+    if (!mh) return FALSE;
 
     /* save the current pen, brush and font */
     hPen = GetCurrentObject(hdc, OBJ_PEN);
diff --git a/dlls/gdi32/opengl.c b/dlls/gdi32/opengl.c
index 925a283bd33..578737994ab 100644
--- a/dlls/gdi32/opengl.c
+++ b/dlls/gdi32/opengl.c
@@ -112,7 +112,7 @@ BOOL WINAPI SetPixelFormat( HDC hdc, INT fmt, const PIXELFORMATDESCRIPTOR *pfd )
     {
         if (!opengl32) opengl32 = LoadLibraryW( opengl32W );
         if (!(wglSetPixelFormat = (void *)GetProcAddress( opengl32, "wglSetPixelFormat" )))
-            return 0;
+            return FALSE;
     }
     return wglSetPixelFormat( hdc, fmt, pfd );
 }
@@ -126,7 +126,7 @@ BOOL WINAPI SwapBuffers( HDC hdc )
     {
         if (!opengl32) opengl32 = LoadLibraryW( opengl32W );
         if (!(wglSwapBuffers = (void *)GetProcAddress( opengl32, "wglSwapBuffers" )))
-            return 0;
+            return FALSE;
     }
     return wglSwapBuffers( hdc );
 }
diff --git a/dlls/gdi32/palette.c b/dlls/gdi32/palette.c
index 81f0aa5716c..fb27f4f5fff 100644
--- a/dlls/gdi32/palette.c
+++ b/dlls/gdi32/palette.c
@@ -319,13 +319,13 @@ BOOL WINAPI AnimatePalette(
         const PALETTEENTRY *pptr = PaletteColors;
 
         palPtr = GDI_GetObjPtr( hPal, OBJ_PAL );
-        if (!palPtr) return 0;
+        if (!palPtr) return FALSE;
 
         pal_entries = palPtr->count;
         if (StartIndex >= pal_entries)
         {
           GDI_ReleaseObj( hPal );
-          return 0;
+          return FALSE;
         }
         if (StartIndex+NumEntries > pal_entries) NumEntries = pal_entries - StartIndex;