diff --git a/cue/format/printer.go b/cue/format/printer.go
index 0d5ed74..79edc1a 100644
--- a/cue/format/printer.go
+++ b/cue/format/printer.go
@@ -133,7 +133,22 @@
 				data[1] >= '0' && data[1] <= '9' {
 				data = "0o" + data[1:]
 			}
+			// Pad trailing dot before multiplier.
+			if p := strings.IndexByte(data, '.'); p >= 0 && data[p+1] > '9' {
+				data = data[:p+1] + "0" + data[p+1:]
+			}
+
 		case token.FLOAT:
+			// Pad leading or trailing dots.
+			switch p := strings.IndexByte(data, '.'); {
+			case p < 0:
+			case p == 0:
+				data = "0" + data
+			case p == len(data)-1:
+				data += "0"
+			case data[p+1] > '9':
+				data = data[:p+1] + "0" + data[p+1:]
+			}
 			if strings.IndexByte(data, 'E') != -1 {
 				data = strings.ToLower(data)
 			}
diff --git a/cue/format/testdata/values.golden b/cue/format/testdata/values.golden
index cd048f6..c8968aa 100644
--- a/cue/format/testdata/values.golden
+++ b/cue/format/testdata/values.golden
@@ -2,5 +2,13 @@
 a: 0e1
 a: 0e+1
 a: 0e1
-a: .3e+1
-a: .3e+1
+a: 0.3e+1
+a: 0.3e+1
+a: 0.3
+a: 3.0
+a: 3.0T
+a: 3.0e100
+
+s: """
+	x\"\"\"
+	"""
diff --git a/cue/format/testdata/values.input b/cue/format/testdata/values.input
index 77a34a4..6203408 100644
--- a/cue/format/testdata/values.input
+++ b/cue/format/testdata/values.input
@@ -4,3 +4,12 @@
 a: 0E1
 a: .3e+1
 a: .3E+1
+a: .3
+a: 3.
+a: 3.T
+a: 3.e100
+
+
+s: """
+    x\"\"\"
+    """
\ No newline at end of file
diff --git a/internal/third_party/yaml/decode_test.go b/internal/third_party/yaml/decode_test.go
index 7b70071..66fb314 100644
--- a/internal/third_party/yaml/decode_test.go
+++ b/internal/third_party/yaml/decode_test.go
@@ -56,7 +56,7 @@
 		"v: 0.1",
 	}, {
 		"v: .1",
-		"v: .1",
+		"v: 0.1",
 	}, {
 		"v: .Inf",
 		"v: +Inf",
@@ -68,7 +68,7 @@
 		"v: -10",
 	}, {
 		"v: -.1",
-		"v: -.1",
+		"v: -0.1",
 	},
 
 	// Simple values.