diff --git a/Source/TransformFunctions/arm_rfft_fast_f16.c b/Source/TransformFunctions/arm_rfft_fast_f16.c
index 95d85d9e..155b0298 100755
--- a/Source/TransformFunctions/arm_rfft_fast_f16.c
+++ b/Source/TransformFunctions/arm_rfft_fast_f16.c
@@ -37,7 +37,7 @@ void stage_rfft_f16(
         float16_t * p,
         float16_t * pOut)
 {
-        uint32_t  k;                                /* Loop Counter */
+        int32_t  k;                                /* Loop Counter */
         float16_t twR, twI;                         /* RFFT Twiddle coefficients */
   const float16_t * pCoeff = S->pTwiddleRFFT;       /* Points to RFFT Twiddle factors */
         float16_t *pA = p;                          /* increasing pointer */
@@ -197,7 +197,7 @@ void merge_rfft_f16(
         float16_t * p,
         float16_t * pOut)
 {
-        uint32_t  k;                                /* Loop Counter */
+        int32_t  k;                                /* Loop Counter */
         float16_t twR, twI;                         /* RFFT Twiddle coefficients */
   const float16_t *pCoeff = S->pTwiddleRFFT;        /* Points to RFFT Twiddle factors */
         float16_t *pA = p;                          /* increasing pointer */
diff --git a/Source/TransformFunctions/arm_rfft_fast_f32.c b/Source/TransformFunctions/arm_rfft_fast_f32.c
index a330dc27..a96a7b2a 100644
--- a/Source/TransformFunctions/arm_rfft_fast_f32.c
+++ b/Source/TransformFunctions/arm_rfft_fast_f32.c
@@ -34,7 +34,7 @@ void stage_rfft_f32(
         float32_t * p,
         float32_t * pOut)
 {
-        uint32_t  k;                                /* Loop Counter */
+        int32_t  k;                                /* Loop Counter */
         float32_t twR, twI;                         /* RFFT Twiddle coefficients */
   const float32_t * pCoeff = S->pTwiddleRFFT;       /* Points to RFFT Twiddle factors */
         float32_t *pA = p;                          /* increasing pointer */
@@ -193,7 +193,7 @@ void merge_rfft_f32(
         float32_t * p,
         float32_t * pOut)
 {
-        uint32_t  k;                                /* Loop Counter */
+        int32_t  k;                                /* Loop Counter */
         float32_t twR, twI;                         /* RFFT Twiddle coefficients */
   const float32_t *pCoeff = S->pTwiddleRFFT;        /* Points to RFFT Twiddle factors */
         float32_t *pA = p;                          /* increasing pointer */
@@ -312,7 +312,7 @@ void stage_rfft_f32(
         float32_t * p,
         float32_t * pOut)
 {
-        uint32_t  k;                                /* Loop Counter */
+        int32_t  k;                                /* Loop Counter */
         float32_t twR, twI;                         /* RFFT Twiddle coefficients */
   const float32_t * pCoeff = S->pTwiddleRFFT;       /* Points to RFFT Twiddle factors */
         float32_t *pA = p;                          /* increasing pointer */
@@ -401,7 +401,7 @@ void merge_rfft_f32(
         float32_t * p,
         float32_t * pOut)
 {
-        uint32_t  k;                                /* Loop Counter */
+        int32_t  k;                                /* Loop Counter */
         float32_t twR, twI;                         /* RFFT Twiddle coefficients */
   const float32_t *pCoeff = S->pTwiddleRFFT;        /* Points to RFFT Twiddle factors */
         float32_t *pA = p;                          /* increasing pointer */
diff --git a/Toolchain/AC6.cmake b/Toolchain/AC6.cmake
index 91012c2f..5a9a1a54 100644
--- a/Toolchain/AC6.cmake
+++ b/Toolchain/AC6.cmake
@@ -53,7 +53,7 @@ function(compilerSpecificCompileOptions PROJECTNAME ROOT)
   endif()
 
   if (ARM_CPU STREQUAL "cortex-m7" )
-        target_compile_options(${PROJECTNAME} PUBLIC "-mfpu=fpv5-sp-d16")
+        target_compile_options(${PROJECTNAME} PUBLIC "-mfpu=fpv5-d16")
   endif()
 
   if (ARM_CPU STREQUAL "cortex-m4" )