diff --git a/cache/binary/tags.go b/cache/binary/tags.go
index dbf86f0..50d79af 100644
--- a/cache/binary/tags.go
+++ b/cache/binary/tags.go
@@ -15,8 +15,9 @@ package binary
 // etc.) are converted to a single ASCII control char (0x01-0x1f)
 
 import (
-	"github.com/omniscale/imposm3/element"
 	"unicode/utf8"
+
+	"github.com/omniscale/imposm3/element"
 )
 
 type codepoint rune
@@ -38,6 +39,8 @@ const maxCodePoint = codepoint('\uF8FF')
 
 var nextCodePoint = codepoint('\uE000')
 
+const escapeRune = '\ufffd' // unicode replacement char
+
 func addTagCodePoint(key, value string) {
 	if nextCodePoint > maxCodePoint {
 		panic("all codepoints used!")
@@ -71,20 +74,33 @@ func tagsFromArray(arr []string) element.Tags {
 	}
 	result := make(element.Tags)
 	for i := 0; i < len(arr); i += 1 {
-		if r, size := utf8.DecodeRuneInString(arr[i]); size >= 3 &&
-			codepoint(r) >= minCodePoint &&
-			codepoint(r) < nextCodePoint {
-			tag, ok := codePointToTag[codepoint(r)]
-			if !ok {
-				panic("missing tag for codepoint")
+		if r, size := utf8.DecodeRuneInString(arr[i]); size >= 3 {
+			if r == escapeRune {
+				// remove escape rune
+				result[arr[i][size:]] = arr[i+1]
+				i++
+				continue
+			} else if codepoint(r) >= minCodePoint &&
+				codepoint(r) < nextCodePoint {
+				tag, ok := codePointToTag[codepoint(r)]
+				if !ok {
+					panic("missing tag for codepoint")
+				}
+				result[tag.Key] = tag.Value
+				continue
 			}
-			result[tag.Key] = tag.Value
 		} else if len(arr[i]) > 0 && arr[i][0] < 32 {
 			result[codePointToCommonKey[arr[i][0]]] = arr[i][1:]
-		} else {
-			result[arr[i]] = arr[i+1]
-			i++
+			continue
 		}
+		if len(arr) <= i+1 {
+			// notify users affected by #112
+			// TODO remove check in the future to avoid misleading message
+			// if a similar issue shows up
+			panic("Internal cache corrupt, see: https://github.com/omniscale/imposm3/issues/122")
+		}
+		result[arr[i]] = arr[i+1]
+		i++
 	}
 	return result
 }
@@ -95,21 +111,32 @@ func tagsAsArray(tags element.Tags) []string {
 	}
 	result := make([]string, 0, 2*len(tags))
 	for key, val := range tags {
-		if valMap, ok := tagsToCodePoint[key]; ok {
-			if codePoint, ok := valMap[val]; ok {
-				result = append(result, string(codePoint))
-				continue
-			}
-		}
-		if codepoint, ok := commonKeys[key]; ok {
-			result = append(result, string(codepoint)+val)
-			continue
-		}
-		result = append(result, key, val)
+		result = appendTag(result, key, val)
 	}
 	return result
 }
 
+func appendTag(arr []string, key, val string) []string {
+	if valMap, ok := tagsToCodePoint[key]; ok {
+		if codePoint, ok := valMap[val]; ok {
+			return append(arr, string(codePoint))
+		}
+	}
+	if codepoint, ok := commonKeys[key]; ok {
+		return append(arr, string(codepoint)+val)
+	}
+	// escape first char/rune if it is a commonKey/tagCodePoint
+	if key[0] < 32 {
+		key = string(escapeRune) + key
+	} else if r, size := utf8.DecodeRuneInString(key); size >= 3 &&
+		(codepoint(r) >= minCodePoint &&
+			codepoint(r) <= maxCodePoint) ||
+		(r == escapeRune) {
+		key = string(escapeRune) + key
+	}
+	return append(arr, key, val)
+}
+
 func init() {
 	//
 	// DO NOT EDIT, REMOVE, REORDER ANY OF THE FOLLOWING LINES!
diff --git a/cache/binary/tags_test.go b/cache/binary/tags_test.go
index c0a18f5..95e455e 100644
--- a/cache/binary/tags_test.go
+++ b/cache/binary/tags_test.go
@@ -1,9 +1,11 @@
 package binary
 
 import (
-	"github.com/omniscale/imposm3/element"
+	"reflect"
 	"sort"
 	"testing"
+
+	"github.com/omniscale/imposm3/element"
 )
 
 func TestTagsAsAndFromArray(t *testing.T) {
@@ -34,6 +36,73 @@ func TestTagsAsAndFromArray(t *testing.T) {
 	}
 }
 
+func TestTagsArrayEncoding(t *testing.T) {
+	for i, check := range []struct {
+		// Test tags with string array of key/value instead of
+		// element.Tags to have fixed order
+		tags     []string
+		expected []string
+	}{
+		{
+			[]string{"name", "foo", "highway", "residential", "oneway", "yes"},
+			[]string{
+				"\x01foo",
+				"\ue001",
+				"\ue008",
+			},
+		},
+		{ // ascii control characters are escaped
+			[]string{"name", "\tfoo", "\tfoo", "bar"},
+			[]string{
+				"\x01\tfoo",
+				"\ufffd\tfoo", "bar",
+			},
+		},
+		{ // private unicode characters are escaped
+			[]string{"\ue008foo", "bar", "\ue008", "baz"},
+			[]string{
+				"\ufffd\ue008foo", "bar",
+				"\ufffd\ue008", "baz",
+			},
+		},
+		{ // replacement characters (our escape token) are escaped as well
+			[]string{"\ufffd\ue008foo", "bar", "\ufffd\ufffd\ufffd\ue008foo", "bar"},
+			[]string{
+				"\ufffd\ufffd\ue008foo", "bar",
+				"\ufffd\ufffd\ufffd\ufffd\ue008foo", "bar",
+			},
+		},
+	} {
+		var actual []string
+		for i := 0; i < len(check.tags); i += 2 {
+			actual = appendTag(actual, check.tags[i], check.tags[i+1])
+		}
+		if len(check.expected) != len(actual) {
+			t.Errorf("case %d: unexpected tag array %#v != %#v", i, actual, check.expected)
+			continue
+		}
+		actualTags := tagsFromArray(actual)
+		expectedTags := make(element.Tags)
+		for i := 0; i < len(check.tags); i += 2 {
+			expectedTags[check.tags[i]] = check.tags[i+1]
+		}
+		if !reflect.DeepEqual(actualTags, expectedTags) {
+			t.Errorf("case %d: unexpected tags %#v != %#v", i, actualTags, expectedTags)
+		}
+	}
+}
+
+func TestTagsArrayIssue122Panic(t *testing.T) {
+	tagsFromArray([]string{"foo", "bar"})
+	defer func() {
+		p := recover()
+		if p == nil {
+			t.Fatal("did not panic")
+		}
+	}()
+	tagsFromArray([]string{"foo"})
+}
+
 func TestCodePoints(t *testing.T) {
 	// codepoints should never change, so check a few for sanity
 	if c := tagsToCodePoint["building"]["yes"]; c != codepoint('\ue000') {