diff --git a/shared-module/audiomixer/Mixer.c b/shared-module/audiomixer/Mixer.c
index 464117fae8d..6af7f5526d1 100644
--- a/shared-module/audiomixer/Mixer.c
+++ b/shared-module/audiomixer/Mixer.c
@@ -72,7 +72,7 @@ void audiomixer_mixer_reset_buffer(audiomixer_mixer_obj_t *self,
 
 __attribute__((always_inline))
 static inline uint32_t add16signed(uint32_t a, uint32_t b) {
-    #if (defined(__ARM_ARCH_7EM__) && (__ARM_ARCH_7EM__ == 1))
+    #if defined(__ARM_FEATURE_DSP) && __ARM_FEATURE_DSP
     return __QADD16(a, b);
     #else
     uint32_t result = 0;
@@ -93,12 +93,13 @@ static inline uint32_t add16signed(uint32_t a, uint32_t b) {
 
 __attribute__((always_inline))
 static inline uint32_t mult16signed(uint32_t val, int32_t lomul, int32_t himul) {
-    #if (defined(__ARM_ARCH_7EM__) && (__ARM_ARCH_7EM__ == 1))
-    lomul <<= 16;
-    himul <<= 16;
+    #if defined(__ARM_FEATURE_DSP) && __ARM_FEATURE_DSP
+    // A level of 1.0 is 1 << 15, so shifting by 16 would overflow into the sign bit.
+    lomul <<= 15;
+    himul <<= 15;
     int32_t hi, lo;
     enum { bits = 16 }; // saturate to 16 bits
-    enum { shift = 15 }; // shift is done automatically
+    enum { shift = 14 }; // smulw shifts by 16, so 14 more gives (val * mul) >> 15
     __asm__ volatile ("smulwb %0, %1, %2" : "=r" (lo) : "r" (lomul), "r" (val));
     __asm__ volatile ("smulwt %0, %1, %2" : "=r" (hi) : "r" (himul), "r" (val));
     __asm__ volatile ("ssat %0, %1, %2, asr %3" : "=r" (lo) : "I" (bits), "r" (lo), "I" (shift));
@@ -108,9 +109,8 @@ static inline uint32_t mult16signed(uint32_t val, int32_t lomul, int32_t himul)
     #else
     uint32_t result = 0;
     for (int8_t i = 0; i < 2; i++) {
-        float mod_mul = (float)(i ? himul : lomul) / (float)((1 << 15) - 1);
         int16_t ai = (val >> (sizeof(uint16_t) * 8 * i));
-        int32_t intermediate = (int32_t)(ai * mod_mul);
+        int32_t intermediate = (ai * (i ? himul : lomul)) >> 15;
         if (intermediate > SHRT_MAX) {
             intermediate = SHRT_MAX;
         } else if (intermediate < SHRT_MIN) {
@@ -124,7 +124,7 @@ static inline uint32_t mult16signed(uint32_t val, int32_t lomul, int32_t himul)
 }
 
 static inline uint32_t tounsigned8(uint32_t val) {
-    #if (defined(__ARM_ARCH_7EM__) && (__ARM_ARCH_7EM__ == 1))
+    #if defined(__ARM_FEATURE_DSP) && __ARM_FEATURE_DSP
     return __UADD8(val, 0x80808080);
     #else
     return val ^ 0x80808080;
@@ -132,7 +132,7 @@ static inline uint32_t tounsigned8(uint32_t val) {
 }
 
 static inline uint32_t tounsigned16(uint32_t val) {
-    #if (defined(__ARM_ARCH_7EM__) && (__ARM_ARCH_7EM__ == 1))
+    #if defined(__ARM_FEATURE_DSP) && __ARM_FEATURE_DSP
     return __UADD16(val, 0x80008000);
     #else
     return val ^ 0x80008000;
@@ -140,7 +140,7 @@ static inline uint32_t tounsigned16(uint32_t val) {
 }
 
 static inline uint32_t tosigned16(uint32_t val) {
-    #if (defined(__ARM_ARCH_7EM__) && (__ARM_ARCH_7EM__ == 1))
+    #if defined(__ARM_FEATURE_DSP) && __ARM_FEATURE_DSP
     return __UADD16(val, 0x80008000);
     #else
     return val ^ 0x80008000;
@@ -156,7 +156,7 @@ static inline uint32_t pack8(uint32_t val) {
 }
 
 static inline uint32_t copy16lsb(uint32_t val) {
-    #if (defined(__ARM_ARCH_7EM__) && (__ARM_ARCH_7EM__ == 1))
+    #if defined(__ARM_FEATURE_DSP) && __ARM_FEATURE_DSP
     return __PKHBT(val, val, 16);
     #else
     val &= 0x0000ffff;
@@ -165,7 +165,7 @@ static inline uint32_t copy16lsb(uint32_t val) {
 }
 
 static inline uint32_t copy16msb(uint32_t val) {
-    #if (defined(__ARM_ARCH_7EM__) && (__ARM_ARCH_7EM__ == 1))
+    #if defined(__ARM_FEATURE_DSP) && __ARM_FEATURE_DSP
     return __PKHTB(val, val, 16);
     #else
     val &= 0xffff0000;
@@ -259,9 +259,9 @@ static void mix_down_one_voice(audiomixer_mixer_obj_t *self,
         uint16_t left_panning_scaled = 32768, right_panning_scaled = 32768;
         if (MP_LIKELY(self->base.channel_count == 2)) {
             if (panning >= 0) {
-                left_panning_scaled = 32767 - panning;
+                left_panning_scaled = 32768 - panning;
             } else {
-                right_panning_scaled = 32767 + panning;
+                right_panning_scaled = 32768 + panning;
             }
         }