diff --git a/libass/ass_cache.c b/libass/ass_cache.c
index 41645c4a48..8c4c91e739 100644
--- a/libass/ass_cache.c
+++ b/libass/ass_cache.c
@@ -228,6 +228,13 @@ void ass_font_cache_done(void)
 	hashmap_done(font_cache);
 }
 
+
+// Create hash/compare functions for bitmap and glyph
+#define CREATE_HASH_FUNCTIONS
+#include "ass_cache_template.c"
+#define CREATE_COMPARISON_FUNCTIONS
+#include "ass_cache_template.c"
+
 //---------------------------------
 // bitmap cache
 
@@ -263,7 +270,8 @@ void ass_bitmap_cache_init(void)
 	bitmap_cache = hashmap_init(sizeof(bitmap_hash_key_t),
 				   sizeof(bitmap_hash_val_t),
 				   0xFFFF + 13,
-				   bitmap_hash_dtor, NULL, NULL);
+				   bitmap_hash_dtor, bitmap_compare,
+				   bitmap_hash);
 }
 
 void ass_bitmap_cache_done(void)
@@ -311,7 +319,7 @@ void ass_glyph_cache_init(void)
 	glyph_cache = hashmap_init(sizeof(glyph_hash_key_t),
 				   sizeof(glyph_hash_val_t),
 				   0xFFFF + 13,
-				   glyph_hash_dtor, NULL, NULL);
+				   glyph_hash_dtor, glyph_compare, glyph_hash);
 }
 
 void ass_glyph_cache_done(void)
diff --git a/libass/ass_cache.h b/libass/ass_cache.h
index 5f6a2ddd94..a76d935992 100644
--- a/libass/ass_cache.h
+++ b/libass/ass_cache.h
@@ -33,24 +33,9 @@ void* ass_font_cache_add(ass_font_t* font);
 void ass_font_cache_done(void);
 
 
-// describes a bitmap; bitmaps with equivalents structs are considered identical
-typedef struct bitmap_hash_key_s {
-	char bitmap; // bool : true = bitmap, false = outline
-	ass_font_t* font;
-	double size; // font size
-	uint32_t ch; // character code
-	unsigned outline; // border width, 16.16 fixed point value
-	int bold, italic;
-	char be; // blur edges
-
-	unsigned scale_x, scale_y; // 16.16
-	int frx, fry, frz; // signed 16.16
-	int shift_x, shift_y; // shift vector that was added to glyph before applying rotation
-	                      // = 0, if frx = fry = frx = 0
-	                      // = (glyph base point) - (rotation origin), otherwise
-	
-	FT_Vector advance; // subpixel shift vector
-} bitmap_hash_key_t;
+// Create definitions for bitmap_hash_key and glyph_hash_key
+#define CREATE_STRUCT_DEFINITIONS
+#include "ass_cache_template.c"
 
 typedef struct bitmap_hash_val_s {
 	bitmap_t* bm; // the actual bitmaps
@@ -64,17 +49,6 @@ bitmap_hash_val_t* cache_find_bitmap(bitmap_hash_key_t* key);
 void ass_bitmap_cache_reset(void);
 void ass_bitmap_cache_done(void);
 
-// describes an outline glyph
-typedef struct glyph_hash_key_s {
-	ass_font_t* font;
-	double size; // font size
-	uint32_t ch; // character code
-	int bold, italic;
-	unsigned scale_x, scale_y; // 16.16
-	FT_Vector advance; // subpixel shift vector
-	unsigned outline; // border width, 16.16
-} glyph_hash_key_t;
-
 typedef struct glyph_hash_val_s {
 	FT_Glyph glyph;
 	FT_Glyph outline_glyph;
diff --git a/libass/ass_cache_template.c b/libass/ass_cache_template.c
new file mode 100644
index 0000000000..5f77190fa1
--- /dev/null
+++ b/libass/ass_cache_template.c
@@ -0,0 +1,87 @@
+#ifdef CREATE_STRUCT_DEFINITIONS
+#undef CREATE_STRUCT_DEFINITIONS
+#define START(funcname, structname) \
+    typedef struct structname {
+#define GENERIC(type, member) \
+        type member;
+#define FTVECTOR(member) \
+        FT_Vector member;
+#define END(typedefnamename) \
+    } typedefnamename;
+
+#elif defined(CREATE_COMPARISON_FUNCTIONS)
+#undef CREATE_COMPARISON_FUNCTIONS
+#define START(funcname, structname) \
+    static int funcname##_compare(void *key1, void *key2, size_t key_size) \
+    { \
+        struct structname *a = key1; \
+        struct structname *b = key2; \
+        return // conditions follow
+#define GENERIC(type, member) \
+            a->member == b->member &&
+#define FTVECTOR(member) \
+            a->member.x == b->member.x && a->member.y == b->member.y &&
+#define END(typedefname) \
+            1; \
+    }
+
+#elif defined(CREATE_HASH_FUNCTIONS)
+#undef CREATE_HASH_FUNCTIONS
+#define START(funcname, structname) \
+    static unsigned funcname##_hash(void *buf, size_t len) \
+    { \
+        struct structname *p = buf; \
+        unsigned hval = FNV1_32A_INIT;
+#define GENERIC(type, member) \
+        hval = fnv_32a_buf(&p->member, sizeof(p->member), hval);
+#define FTVECTOR(member) GENERIC(, member.x); GENERIC(, member.y);
+#define END(typedefname) \
+        return hval; \
+    }
+
+#else
+#error missing defines
+#endif
+
+
+
+// describes a bitmap; bitmaps with equivalents structs are considered identical
+START(bitmap, bipmap_hash_key_s)
+    GENERIC(char, bitmap) // bool : true = bitmap, false = outline
+    GENERIC(ass_font_t *, font)
+    GENERIC(double, size) // font size
+    GENERIC(uint32_t, ch) // character code
+    GENERIC(unsigned, outline) // border width, 16.16 fixed point value
+    GENERIC(int, bold)
+    GENERIC(int, italic)
+    GENERIC(char, be) // blur edges
+    GENERIC(unsigned, scale_x) // 16.16
+    GENERIC(unsigned, scale_y) // 16.16
+    GENERIC(int, frx) // signed 16.16
+    GENERIC(int, fry) // signed 16.16
+    GENERIC(int, frz) // signed 16.16
+    // shift vector that was added to glyph before applying rotation
+    // = 0, if frx = fry = frx = 0
+    // = (glyph base point) - (rotation origin), otherwise
+    GENERIC(int, shift_x)
+    GENERIC(int, shift_y)
+    FTVECTOR(advance) // subpixel shift vector
+END(bitmap_hash_key_t)
+
+// describes an outline glyph
+START(glyph, glyph_hash_key_s)
+    GENERIC(ass_font_t *, font)
+    GENERIC(double, size) // font size
+    GENERIC(uint32_t, ch) // character code
+    GENERIC(int, bold)
+    GENERIC(int, italic)
+    GENERIC(unsigned, scale_x) // 16.16
+    GENERIC(unsigned, scale_y) // 16.16
+    FTVECTOR(advance) // subpixel shift vector
+    GENERIC(unsigned, outline) // border width, 16.16
+END(glyph_hash_key_t)
+
+#undef START
+#undef GENERIC
+#undef FTVECTOR
+#undef END