diff --git a/src/internal/bytealg/index_ppc64x.s b/src/internal/bytealg/index_ppc64x.s
index 38442ce27ce..735159cd8e2 100644
--- a/src/internal/bytealg/index_ppc64x.s
+++ b/src/internal/bytealg/index_ppc64x.s
@@ -614,7 +614,7 @@ index4loop:
 next4:
 	VSPLTISB $0, V10            // Clear
 	MOVD     $3, R9             // Number of bytes beyond 16
-	LXVB16X  (R7)(R9), V3       // Load 16 bytes @R7 into V2
+	LXVB16X  (R7)(R9), V3       // Load 16 bytes @R7 into V3
 	VSLDOI   $13, V3, V10, V3   // Shift left last 3 bytes
 	VSLDOI   $1, V2, V3, V4     // V4=(V2:V3)<<1
 	VSLDOI   $2, V2, V3, V9     // V9=(V2:V3)<<2
@@ -654,11 +654,11 @@ index2to16:
 
 	ADD $19, R7, R9    // To check 4 indices per iteration, need at least 16+3 bytes
 	CMP R9, LASTBYTE
-	BGT index2to16tail
-
 	// At least 16 bytes of string left
 	// Mask the number of bytes in sep
 	VSPLTISB $0, V10            // Clear
+	BGT index2to16tail
+
 	MOVD     $3, R17            // Number of bytes beyond 16
 
 index2to16loop:
@@ -720,14 +720,15 @@ extra2:
 	ADD        $1, R7          // Not found, try next partial string
 	CMP        R7, LASTSTR     // Check for end of string
 	BGT        notfound        // If at end, then not found
-	VSLDOI     $1, V1, V25, V1 // Shift string left by 1 byte
+	VOR        V1, V1, V4      // save remaining string
+	VSLDOI     $1, V1, V25, V1 // Shift string left by 1 byte for 17th byte
 	VAND       V1, SEPMASK, V2 // Just compare size of sep
 	VCMPEQUBCC V0, V2, V3      // Compare sep and partial string
 	BLT        CR6, found      // Found
 	ADD        $1, R7          // Not found, try next partial string
 	CMP        R7, LASTSTR     // Check for end of string
 	BGT        notfound        // If at end, then not found
-	VSLDOI     $1, V1, V25, V1 // Shift string left by 1 byte
+	VSLDOI     $2, V4, V25, V1 // Shift saved string left by 2 bytes for 18th byte
 	BR         index2to16next  // Check the remaining partial string in index2to16next
 
 short:
diff --git a/src/strings/strings_test.go b/src/strings/strings_test.go
index 27489c2d165..3991d127511 100644
--- a/src/strings/strings_test.go
+++ b/src/strings/strings_test.go
@@ -54,6 +54,11 @@ var indexTests = []IndexTest{
 	{"foo", "", 0},
 	{"foo", "o", 1},
 	{"abcABCabc", "A", 3},
+	{"jrzm6jjhorimglljrea4w3rlgosts0w2gia17hno2td4qd1jz", "jz", 47},
+	{"ekkuk5oft4eq0ocpacknhwouic1uua46unx12l37nioq9wbpnocqks6", "ks6", 52},
+	{"999f2xmimunbuyew5vrkla9cpwhmxan8o98ec", "98ec", 33},
+	{"9lpt9r98i04k8bz6c6dsrthb96bhi", "96bhi", 24},
+	{"55u558eqfaod2r2gu42xxsu631xf0zobs5840vl", "5840vl", 33},
 	// cases with one byte strings - test special case in Index()
 	{"", "a", -1},
 	{"x", "a", -1},