diff --git a/src/hb-wasm-api-blob.hh b/src/hb-wasm-api-blob.hh
index afcbd2672..26b022bc3 100644
--- a/src/hb-wasm-api-blob.hh
+++ b/src/hb-wasm-api-blob.hh
@@ -31,9 +31,8 @@ namespace hb {
 namespace wasm {
 
 
-void
-blob_free (HB_WASM_EXEC_ENV
-	   ptr_d(blob_t, blob))
+HB_WASM_API (void, blob_free) (HB_WASM_EXEC_ENV
+			       ptr_d(blob_t, blob))
 {
   HB_OUT_PARAM (blob_t, blob);
   if (unlikely (!blob))
diff --git a/src/hb-wasm-api-buffer.hh b/src/hb-wasm-api-buffer.hh
index d75cb6231..40f5700a6 100644
--- a/src/hb-wasm-api-buffer.hh
+++ b/src/hb-wasm-api-buffer.hh
@@ -35,26 +35,9 @@ namespace wasm {
 static_assert (sizeof (glyph_info_t) == sizeof (hb_glyph_info_t), "");
 static_assert (sizeof (glyph_position_t) == sizeof (hb_glyph_position_t), "");
 
-void
-buffer_contents_free (HB_WASM_EXEC_ENV
-		      ptr_d(buffer_contents_t, contents))
-{
-  HB_OUT_PARAM (buffer_contents_t, contents);
-  if (unlikely (!contents))
-    return;
-
-  module_free (contents->info);
-  module_free (contents->pos);
-
-  contents->info = nullref;
-  contents->pos = nullref;
-  contents->length = 0;
-}
-
-void
- buffer_contents_realloc (HB_WASM_EXEC_ENV
-			  ptr_d(buffer_contents_t, contents),
-			  uint32_t size)
+HB_WASM_API (void, buffer_contents_realloc) (HB_WASM_EXEC_ENV
+					     ptr_d(buffer_contents_t, contents),
+					     uint32_t size)
 {
   HB_OUT_PARAM (buffer_contents_t, contents);
   if (unlikely (!contents))
@@ -83,9 +66,23 @@ void
   contents->length = size;
 }
 
-void
-buffer_copy_contents (HB_WASM_EXEC_ENV_COMPOUND
-		      ptr_d(buffer_t, buffer))
+HB_WASM_API (void, buffer_contents_free) (HB_WASM_EXEC_ENV
+					  ptr_d(buffer_contents_t, contents))
+{
+  HB_OUT_PARAM (buffer_contents_t, contents);
+  if (unlikely (!contents))
+    return;
+
+  module_free (contents->info);
+  module_free (contents->pos);
+
+  contents->info = nullref;
+  contents->pos = nullref;
+  contents->length = 0;
+}
+
+HB_WASM_API_COMPOUND (buffer_contents_t, buffer_copy_contents) (HB_WASM_EXEC_ENV_COMPOUND
+								ptr_d(buffer_t, buffer))
 {
   HB_RETURN_STRUCT (buffer_contents_t, ret);
   HB_REF2OBJ (buffer);
@@ -99,10 +96,9 @@ buffer_copy_contents (HB_WASM_EXEC_ENV_COMPOUND
   ret.pos = wasm_runtime_module_dup_data (module_inst, (const char *) buffer->pos, length * sizeof (buffer->pos[0]));
 }
 
-bool_t
-buffer_set_contents (HB_WASM_EXEC_ENV
-		     ptr_d(buffer_t, buffer),
-		     ptr_d(const buffer_contents_t, contents))
+HB_WASM_API (bool_t, buffer_set_contents) (HB_WASM_EXEC_ENV
+					   ptr_d(buffer_t, buffer),
+					   ptr_d(const buffer_contents_t, contents))
 {
   HB_REF2OBJ (buffer);
   HB_OUT_PARAM (buffer_contents_t, contents);
@@ -128,27 +124,24 @@ buffer_set_contents (HB_WASM_EXEC_ENV
   return true;
 }
 
-direction_t
-buffer_get_direction (HB_WASM_EXEC_ENV
-		      ptr_d(buffer_t, buffer))
+HB_WASM_API (direction_t, buffer_get_direction) (HB_WASM_EXEC_ENV
+						 ptr_d(buffer_t, buffer))
 {
   HB_REF2OBJ (buffer);
 
   return (direction_t) hb_buffer_get_direction (buffer);
 }
 
-void
-buffer_reverse (HB_WASM_EXEC_ENV
-		ptr_d(buffer_t, buffer))
+HB_WASM_API (void, buffer_reverse) (HB_WASM_EXEC_ENV
+				    ptr_d(buffer_t, buffer))
 {
   HB_REF2OBJ (buffer);
 
   hb_buffer_reverse (buffer);
 }
 
-void
-buffer_reverse_clusters (HB_WASM_EXEC_ENV
-			 ptr_d(buffer_t, buffer))
+HB_WASM_API (void, buffer_reverse_clusters) (HB_WASM_EXEC_ENV
+					     ptr_d(buffer_t, buffer))
 {
   HB_REF2OBJ (buffer);
 
diff --git a/src/hb-wasm-api-face.hh b/src/hb-wasm-api-face.hh
index 8e086d140..1d891dadf 100644
--- a/src/hb-wasm-api-face.hh
+++ b/src/hb-wasm-api-face.hh
@@ -31,10 +31,9 @@ namespace hb {
 namespace wasm {
 
 
-void
-face_reference_table (HB_WASM_EXEC_ENV_COMPOUND
-		      ptr_d(face_t, face),
-		      tag_t table_tag)
+HB_WASM_API_COMPOUND (blob_t, face_reference_table) (HB_WASM_EXEC_ENV_COMPOUND
+						     ptr_d(face_t, face),
+						     tag_t table_tag)
 {
   HB_RETURN_STRUCT (blob_t, ret);
   HB_REF2OBJ (face);
@@ -50,9 +49,8 @@ face_reference_table (HB_WASM_EXEC_ENV_COMPOUND
   hb_blob_destroy (blob);
 }
 
-unsigned
-face_get_upem (HB_WASM_EXEC_ENV
-	       ptr_d(face_t, face))
+HB_WASM_API (unsigned, face_get_upem) (HB_WASM_EXEC_ENV
+				       ptr_d(face_t, face))
 {
   HB_REF2OBJ (face);
 
diff --git a/src/hb-wasm-api-font.hh b/src/hb-wasm-api-font.hh
index 89a264bd3..e5a6ff7fd 100644
--- a/src/hb-wasm-api-font.hh
+++ b/src/hb-wasm-api-font.hh
@@ -31,9 +31,8 @@ namespace hb {
 namespace wasm {
 
 
-ptr_t(face_t)
-font_get_face (HB_WASM_EXEC_ENV
-	       ptr_d(font_t, font))
+HB_WASM_API (ptr_t(face_t), font_get_face) (HB_WASM_EXEC_ENV
+					    ptr_d(font_t, font))
 {
   HB_REF2OBJ (font);
 
@@ -43,11 +42,10 @@ font_get_face (HB_WASM_EXEC_ENV
   return faceref;
 }
 
-void
-font_get_scale (HB_WASM_EXEC_ENV
-		ptr_d(font_t, font),
-		ptr_d(int32_t, x_scale),
-		ptr_d(int32_t, y_scale))
+HB_WASM_API (void, font_get_scale) (HB_WASM_EXEC_ENV
+				    ptr_d(font_t, font),
+				    ptr_d(int32_t, x_scale),
+				    ptr_d(int32_t, y_scale))
 {
   HB_REF2OBJ (font);
 
@@ -57,11 +55,10 @@ font_get_scale (HB_WASM_EXEC_ENV
   hb_font_get_scale (font, x_scale, y_scale);
 }
 
-codepoint_t
-font_get_glyph (HB_WASM_EXEC_ENV
-		ptr_d(font_t, font),
-		codepoint_t unicode,
-		codepoint_t variation_selector)
+HB_WASM_API (codepoint_t, font_get_glyph) (HB_WASM_EXEC_ENV
+					      ptr_d(font_t, font),
+					      codepoint_t unicode,
+					      codepoint_t variation_selector)
 {
   HB_REF2OBJ (font);
   codepoint_t glyph;
@@ -70,19 +67,17 @@ font_get_glyph (HB_WASM_EXEC_ENV
   return glyph;
 }
 
-hb_position_t
-font_get_glyph_h_advance (HB_WASM_EXEC_ENV
-			  ptr_d(font_t, font),
-			  codepoint_t glyph)
+HB_WASM_API (position_t, font_get_glyph_h_advance) (HB_WASM_EXEC_ENV
+						    ptr_d(font_t, font),
+						    codepoint_t glyph)
 {
   HB_REF2OBJ (font);
   return hb_font_get_glyph_h_advance (font, glyph);
 }
 
-hb_position_t
-font_get_glyph_v_advance (HB_WASM_EXEC_ENV
-			  ptr_d(font_t, font),
-			  codepoint_t glyph)
+HB_WASM_API (position_t, font_get_glyph_v_advance) (HB_WASM_EXEC_ENV
+						    ptr_d(font_t, font),
+						    codepoint_t glyph)
 {
   HB_REF2OBJ (font);
   return hb_font_get_glyph_v_advance (font, glyph);
@@ -90,11 +85,10 @@ font_get_glyph_v_advance (HB_WASM_EXEC_ENV
 
 static_assert (sizeof (glyph_extents_t) == sizeof (hb_glyph_extents_t), "");
 
-bool_t
-font_get_glyph_extents (HB_WASM_EXEC_ENV
-			ptr_d(font_t, font),
-			codepoint_t glyph,
-			ptr_d(glyph_extents_t, extents))
+HB_WASM_API (bool_t, font_get_glyph_extents) (HB_WASM_EXEC_ENV
+					      ptr_d(font_t, font),
+					      codepoint_t glyph,
+					      ptr_d(glyph_extents_t, extents))
 {
   HB_REF2OBJ (font);
   HB_OUT_PARAM (glyph_extents_t, extents);
@@ -105,11 +99,10 @@ font_get_glyph_extents (HB_WASM_EXEC_ENV
 				    (hb_glyph_extents_t *) extents);
 }
 
-void
-font_glyph_to_string (HB_WASM_EXEC_ENV
-		      ptr_d(font_t, font),
-		      codepoint_t glyph,
-		      char *s, uint32_t size)
+HB_WASM_API (void, font_glyph_to_string) (HB_WASM_EXEC_ENV
+					  ptr_d(font_t, font),
+					  codepoint_t glyph,
+					  char *s, uint32_t size)
 {
   HB_REF2OBJ (font);
 
diff --git a/src/hb-wasm-api-shape.hh b/src/hb-wasm-api-shape.hh
index 0a65e471b..d141b3c69 100644
--- a/src/hb-wasm-api-shape.hh
+++ b/src/hb-wasm-api-shape.hh
@@ -31,11 +31,10 @@ namespace hb {
 namespace wasm {
 
 
-bool_t
-shape_with (HB_WASM_EXEC_ENV
-	    ptr_d(font_t, font),
-	    ptr_d(buffer_t, buffer),
-	    const char *shaper)
+HB_WASM_INTERFACE (bool_t, shape_with) (HB_WASM_EXEC_ENV
+				        ptr_d(font_t, font),
+				        ptr_d(buffer_t, buffer),
+					const char *shaper)
 {
   HB_REF2OBJ (font);
   HB_REF2OBJ (buffer);
diff --git a/src/hb-wasm-api.hh b/src/hb-wasm-api.hh
index 5b99c8030..f5ef9e487 100644
--- a/src/hb-wasm-api.hh
+++ b/src/hb-wasm-api.hh
@@ -43,7 +43,6 @@
 
 #include "hb-wasm-api.h"
 
-#undef HB_WASM_API
 #undef HB_WASM_BEGIN_DECLS
 #undef HB_WASM_END_DECLS