diff --git a/src/hb-bit-set-invertible.hh b/src/hb-bit-set-invertible.hh
index caea47d8d..512107ffd 100644
--- a/src/hb-bit-set-invertible.hh
+++ b/src/hb-bit-set-invertible.hh
@@ -100,7 +100,7 @@ struct hb_bit_set_invertible_t
 
   void add (hb_codepoint_t g) { unlikely (inverted) ? s.del (g) : s.add (g); }
   bool add_range (hb_codepoint_t a, hb_codepoint_t b)
-  { return unlikely (inverted) ? (s.del_range (a, b), true) : s.add_range (a, b); }
+  { return unlikely (inverted) ? ((void) s.del_range (a, b), true) : s.add_range (a, b); }
 
   template <typename T>
   void add_array (const T *array, unsigned int count, unsigned int stride=sizeof(T))
diff --git a/src/hb-coretext.cc b/src/hb-coretext.cc
index 6ccc1b0a2..2e221cbd1 100644
--- a/src/hb-coretext.cc
+++ b/src/hb-coretext.cc
@@ -1151,7 +1151,7 @@ resize_and_retry:
 	pos->x_offset = info->var1.i32;
 	pos->y_offset = info->var2.i32;
 
-	info++, pos++;
+	info++; pos++;
       }
     else
       for (unsigned int i = 0; i < count; i++)
@@ -1160,7 +1160,7 @@ resize_and_retry:
 	pos->x_offset = info->var1.i32;
 	pos->y_offset = info->var2.i32;
 
-	info++, pos++;
+	info++; pos++;
       }
 
     /* Fix up clusters so that we never return out-of-order indices;
diff --git a/src/hb-ot-var-fvar-table.hh b/src/hb-ot-var-fvar-table.hh
index e06655868..c5c476bc0 100644
--- a/src/hb-ot-var-fvar-table.hh
+++ b/src/hb-ot-var-fvar-table.hh
@@ -213,7 +213,7 @@ struct fvar
     if (!axis_index) axis_index = &i;
     *axis_index = HB_OT_VAR_NO_AXIS_INDEX;
     auto axes = get_axes ();
-    return axes.lfind (tag, axis_index) && (axes[*axis_index].get_axis_deprecated (info), true);
+    return axes.lfind (tag, axis_index) && ((void) axes[*axis_index].get_axis_deprecated (info), true);
   }
 #endif
   bool
@@ -221,7 +221,7 @@ struct fvar
   {
     unsigned i;
     auto axes = get_axes ();
-    return axes.lfind (tag, &i) && (axes[i].get_axis_info (i, info), true);
+    return axes.lfind (tag, &i) && ((void) axes[i].get_axis_info (i, info), true);
   }
 
   int normalize_axis_value (unsigned int axis_index, float v) const
diff --git a/src/hb-repacker.hh b/src/hb-repacker.hh
index c9075fa1e..19c2c2f34 100644
--- a/src/hb-repacker.hh
+++ b/src/hb-repacker.hh
@@ -760,7 +760,7 @@ struct graph_t
   }
 
   bool check_success (bool success)
-  { return this->successful && (success || (err_other_error (), false)); }
+  { return this->successful && (success || ((void) err_other_error (), false)); }
 
   /*
    * Creates a map from objid to # of incoming edges.
diff --git a/src/hb-subset.cc b/src/hb-subset.cc
index de29f8ce1..428a9dd12 100644
--- a/src/hb-subset.cc
+++ b/src/hb-subset.cc
@@ -336,7 +336,7 @@ _is_table_present (hb_face_t *source, hb_tag_t tag)
 
   hb_tag_t table_tags[32];
   unsigned offset = 0, num_tables = ARRAY_LENGTH (table_tags);
-  while ((hb_face_get_table_tags (source, offset, &num_tables, table_tags), num_tables))
+  while (((void) hb_face_get_table_tags (source, offset, &num_tables, table_tags), num_tables))
   {
     for (unsigned i = 0; i < num_tables; ++i)
       if (table_tags[i] == tag)
@@ -499,7 +499,7 @@ hb_subset_plan_execute_or_fail (hb_subset_plan_t *plan)
   hb_vector_t<char> buf;
   buf.alloc (4096 - 16);
 
-  while ((_get_table_tags (plan, offset, &num_tables, table_tags), num_tables))
+  while (((void) _get_table_tags (plan, offset, &num_tables, table_tags), num_tables))
   {
     for (unsigned i = 0; i < num_tables; ++i)
     {
diff --git a/src/hb.hh b/src/hb.hh
index 14872e2a4..d574f0881 100644
--- a/src/hb.hh
+++ b/src/hb.hh
@@ -64,6 +64,7 @@
 #pragma GCC diagnostic error   "-Wbitwise-instead-of-logical"
 #pragma GCC diagnostic error   "-Wcast-align"
 #pragma GCC diagnostic error   "-Wcast-function-type"
+#pragma GCC diagnostic error   "-Wcomma"
 #pragma GCC diagnostic error   "-Wdelete-non-virtual-dtor"
 #pragma GCC diagnostic error   "-Wembedded-directive"
 #pragma GCC diagnostic error   "-Wextra-semi-stmt"