diff --git a/sljit_src/sljitNativeARM_32.c b/sljit_src/sljitNativeARM_32.c
index ea835f29..da79a80d 100644
--- a/sljit_src/sljitNativeARM_32.c
+++ b/sljit_src/sljitNativeARM_32.c
@@ -2676,7 +2676,7 @@ SLJIT_API_FUNC_ATTRIBUTE sljit_s32 sljit_get_register_index(sljit_s32 type, slji
 	if (type == SLJIT_FLOAT_REGISTER || type == SLJIT_SIMD_REG_64)
 		return freg_map[reg];
 
-	if (type != SLJIT_SIMD_REG_128)
+	if (type == SLJIT_SIMD_REG_128)
 		return freg_map[reg] & ~0x1;
 
 	return -1;
diff --git a/sljit_src/sljitNativeARM_T2_32.c b/sljit_src/sljitNativeARM_T2_32.c
index b2a54dbb..f97b3cf9 100644
--- a/sljit_src/sljitNativeARM_T2_32.c
+++ b/sljit_src/sljitNativeARM_T2_32.c
@@ -2244,7 +2244,7 @@ SLJIT_API_FUNC_ATTRIBUTE sljit_s32 sljit_get_register_index(sljit_s32 type, slji
 	if (type == SLJIT_FLOAT_REGISTER || type == SLJIT_SIMD_REG_64)
 		return freg_map[reg];
 
-	if (type != SLJIT_SIMD_REG_128)
+	if (type == SLJIT_SIMD_REG_128)
 		return freg_map[reg] & ~0x1;
 
 	return -1;
diff --git a/sljit_src/sljitNativeS390X.c b/sljit_src/sljitNativeS390X.c
index cfd7e392..18f91706 100644
--- a/sljit_src/sljitNativeS390X.c
+++ b/sljit_src/sljitNativeS390X.c
@@ -3187,7 +3187,7 @@ SLJIT_API_FUNC_ATTRIBUTE sljit_s32 sljit_get_register_index(sljit_s32 type, slji
 	if (type == SLJIT_GP_REGISTER)
 		return (sljit_s32)gpr(reg);
 
-	if (type != SLJIT_FLOAT_REGISTER)
+	if (type != SLJIT_FLOAT_REGISTER && type != SLJIT_SIMD_REG_128)
 		return -1;
 
 	return (sljit_s32)freg_map[reg];
diff --git a/test_src/sljitTestSimd.h b/test_src/sljitTestSimd.h
index 3758a640..93e266c6 100644
--- a/test_src/sljitTestSimd.h
+++ b/test_src/sljitTestSimd.h
@@ -81,6 +81,12 @@ static void test_simd1(void)
 	sljit_u8 data[63 + 880];
 	sljit_s32 vs0 = SLJIT_NUMBER_OF_SAVED_VECTOR_REGISTERS > 0 ? SLJIT_VS0 : SLJIT_VR5;
 
+	SLJIT_ASSERT(sljit_get_register_index(SLJIT_SIMD_REG_128, SLJIT_VR0) != -1
+		&& sljit_get_register_index(SLJIT_SIMD_REG_128, SLJIT_TMP_DEST_VREG) != -1);
+
+	SLJIT_ASSERT(SLJIT_NUMBER_OF_SAVED_VECTOR_REGISTERS == 0
+		|| sljit_get_register_index(SLJIT_SIMD_REG_128, SLJIT_VS0) != -1);
+
 	if (verbose)
 		printf("Run test_simd1\n");
 
@@ -235,6 +241,8 @@ static void test_simd1(void)
 	FAILED(!check_simd_mov(buf + 288, 239, 16), "test_simd1 case 6 failed\n");
 	FAILED(!check_simd_mov(buf + 344, 176, 16), "test_simd1 case 7 failed\n");
 #if IS_ARM
+	SLJIT_ASSERT(sljit_get_register_index(SLJIT_SIMD_REG_64, SLJIT_VR0) != -1
+		&& sljit_get_register_index(SLJIT_SIMD_REG_64, SLJIT_TMP_DEST_VREG) != -1);
 	FAILED(!check_simd_mov(buf + 384, 88, 8), "test_simd1 case 8 failed\n");
 	FAILED(!check_simd_mov(buf + 402, 197, 8), "test_simd1 case 9 failed\n");
 #endif /* IS_ARM */
@@ -247,6 +255,8 @@ static void test_simd1(void)
 #endif /* IS_ARM */
 
 	if (supported[0]) {
+		SLJIT_ASSERT(sljit_get_register_index(SLJIT_SIMD_REG_256, SLJIT_VR0) != -1
+			&& sljit_get_register_index(SLJIT_SIMD_REG_256, SLJIT_TMP_DEST_VREG) != -1);
 		FAILED(!check_simd_mov(buf + 768, 85, 32), "test_simd1 case 15 failed\n");
 		FAILED(!check_simd_mov(buf + 834, 215, 32), "test_simd1 case 16 failed\n");
 	}