diff --git a/apps/codecs/libmusepack/decoder.h b/apps/codecs/libmusepack/decoder.h
index e36425bd1e..1f78d53c8d 100644
--- a/apps/codecs/libmusepack/decoder.h
+++ b/apps/codecs/libmusepack/decoder.h
@@ -113,7 +113,7 @@ typedef struct mpc_decoder_t {
     mpc_uint8_t   SeekTable_Step;
 
 #ifdef MPC_FIXED_POINT
-    unsigned char SCF_shift[256];
+    mpc_uint8_t   SCF_shift[256];
 #endif
 
     MPC_SAMPLE_FORMAT V_L[MPC_V_MEM + 960];
diff --git a/apps/codecs/libmusepack/musepack.h b/apps/codecs/libmusepack/musepack.h
index 5d1ad0de3f..9bdebf8b04 100644
--- a/apps/codecs/libmusepack/musepack.h
+++ b/apps/codecs/libmusepack/musepack.h
@@ -66,6 +66,16 @@ extern "C" {
 #endif
 #endif
 
+#ifndef ICODE_ATTR_MPC_LARGE_IRAM
+#if (CONFIG_CPU == PP5022) || (CONFIG_CPU == PP5024)
+/* PP5022/24 have 128KB of IRAM and have better performance with ICODE_ATTR */
+#define ICODE_ATTR_MPC_LARGE_IRAM ICODE_ATTR
+#else
+/* all other targets either haven't enough IRAM or performance suffers */
+#define ICODE_ATTR_MPC_LARGE_IRAM
+#endif
+#endif
+
 #ifdef ROCKBOX_LITTLE_ENDIAN
 #define MPC_LITTLE_ENDIAN
 #endif
diff --git a/apps/codecs/libmusepack/synth_filter.c b/apps/codecs/libmusepack/synth_filter.c
index aed5d75fb1..faf014c90d 100644
--- a/apps/codecs/libmusepack/synth_filter.c
+++ b/apps/codecs/libmusepack/synth_filter.c
@@ -198,7 +198,11 @@ static const MPC_SAMPLE_FORMAT  Di_opt [32] [16] ICONST_ATTR = {
 #define INVCOS30 MPC_MAKE_INVCOS( 684664578)
 #define INVCOS31 MPC_MAKE_INVCOS(1367679739)
 
-static inline void 
+void 
+mpc_calculate_new_V ( const MPC_SAMPLE_FORMAT * Sample, MPC_SAMPLE_FORMAT * V )
+ICODE_ATTR_MPC_LARGE_IRAM;
+
+void 
 mpc_calculate_new_V ( const MPC_SAMPLE_FORMAT * Sample, MPC_SAMPLE_FORMAT * V )
 {
     // Calculating new V-buffer values for left channel
@@ -453,7 +457,7 @@ mpc_calculate_new_V ( const MPC_SAMPLE_FORMAT * Sample, MPC_SAMPLE_FORMAT * V )
     //                    total: 111 adds, 107 subs, 80 muls,  80 shifts
 }
 
-static inline void 
+static void 
 mpc_decoder_windowing_D(MPC_SAMPLE_FORMAT * Data, const MPC_SAMPLE_FORMAT * V)
 {
    const MPC_SAMPLE_FORMAT *D = (const MPC_SAMPLE_FORMAT *) &Di_opt;