diff --git a/x/evidence/legacy/v038/types.go b/x/evidence/legacy/v038/types.go
index f438e2bec562..994f718ca5fd 100644
--- a/x/evidence/legacy/v038/types.go
+++ b/x/evidence/legacy/v038/types.go
@@ -91,7 +91,7 @@ func (e Equivocation) Hash() tmbytes.HexBytes {
 
 // ValidateBasic performs basic stateless validation checks on an Equivocation object.
 func (e Equivocation) ValidateBasic() error {
-	if e.Time.IsZero() {
+	if e.Time.Unix() <= 0 {
 		return fmt.Errorf("invalid equivocation time: %s", e.Time)
 	}
 	if e.Height < 1 {
diff --git a/x/evidence/types/evidence.go b/x/evidence/types/evidence.go
index 8558623baa67..95705cc5b937 100644
--- a/x/evidence/types/evidence.go
+++ b/x/evidence/types/evidence.go
@@ -43,7 +43,7 @@ func (e *Equivocation) Hash() tmbytes.HexBytes {
 
 // ValidateBasic performs basic stateless validation checks on an Equivocation object.
 func (e *Equivocation) ValidateBasic() error {
-	if e.Time.IsZero() {
+	if e.Time.Unix() <= 0 {
 		return fmt.Errorf("invalid equivocation time: %s", e.Time)
 	}
 	if e.Height < 1 {
diff --git a/x/ibc/light-clients/07-tendermint/types/consensus_state.go b/x/ibc/light-clients/07-tendermint/types/consensus_state.go
index b581983944fd..adb469a3d108 100644
--- a/x/ibc/light-clients/07-tendermint/types/consensus_state.go
+++ b/x/ibc/light-clients/07-tendermint/types/consensus_state.go
@@ -48,11 +48,8 @@ func (cs ConsensusState) ValidateBasic() error {
 	if err := tmtypes.ValidateHash(cs.NextValidatorsHash); err != nil {
 		return sdkerrors.Wrap(err, "next validators hash is invalid")
 	}
-	if cs.Timestamp.IsZero() {
-		return sdkerrors.Wrap(clienttypes.ErrInvalidConsensus, "timestamp cannot be zero Unix time")
-	}
-	if cs.Timestamp.UnixNano() < 0 {
-		return sdkerrors.Wrap(clienttypes.ErrInvalidConsensus, "timestamp cannot be negative Unix time")
+	if cs.Timestamp.Unix() <= 0 {
+		return sdkerrors.Wrap(clienttypes.ErrInvalidConsensus, "timestamp must be a positive Unix time")
 	}
 	return nil
 }
diff --git a/x/upgrade/keeper/keeper.go b/x/upgrade/keeper/keeper.go
index 0cf619cf36fe..1092885bcb3f 100644
--- a/x/upgrade/keeper/keeper.go
+++ b/x/upgrade/keeper/keeper.go
@@ -60,7 +60,7 @@ func (k Keeper) ScheduleUpgrade(ctx sdk.Context, plan types.Plan) error {
 		return err
 	}
 
-	if !plan.Time.IsZero() {
+	if plan.Time.Unix() > 0 {
 		if !plan.Time.After(ctx.BlockHeader().Time) {
 			return sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "upgrade cannot be scheduled in the past")
 		}
diff --git a/x/upgrade/legacy/v038/types.go b/x/upgrade/legacy/v038/types.go
index fb06a6dc5a1c..db833477bf23 100644
--- a/x/upgrade/legacy/v038/types.go
+++ b/x/upgrade/legacy/v038/types.go
@@ -64,10 +64,11 @@ func (p Plan) ValidateBasic() error {
 	if p.Height < 0 {
 		return sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "height cannot be negative")
 	}
-	if p.Time.IsZero() && p.Height == 0 {
+	isValidTime := p.Time.Unix() > 0
+	if !isValidTime && p.Height == 0 {
 		return sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "must set either time or height")
 	}
-	if !p.Time.IsZero() && p.Height != 0 {
+	if isValidTime && p.Height != 0 {
 		return sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "cannot set both time and height")
 	}
 
@@ -76,7 +77,7 @@ func (p Plan) ValidateBasic() error {
 
 // ShouldExecute returns true if the Plan is ready to execute given the current context
 func (p Plan) ShouldExecute(ctx sdk.Context) bool {
-	if !p.Time.IsZero() {
+	if p.Time.Unix() > 0 {
 		return !ctx.BlockTime().Before(p.Time)
 	}
 	if p.Height > 0 {
@@ -87,7 +88,7 @@ func (p Plan) ShouldExecute(ctx sdk.Context) bool {
 
 // DueAt is a string representation of when this plan is due to be executed
 func (p Plan) DueAt() string {
-	if !p.Time.IsZero() {
+	if p.Time.Unix() > 0 {
 		return fmt.Sprintf("time: %s", p.Time.UTC().Format(time.RFC3339))
 	}
 	return fmt.Sprintf("height: %d", p.Height)
diff --git a/x/upgrade/types/plan.go b/x/upgrade/types/plan.go
index 2cbacd60b0be..aa1a0601ffca 100644
--- a/x/upgrade/types/plan.go
+++ b/x/upgrade/types/plan.go
@@ -39,13 +39,13 @@ func (p Plan) ValidateBasic() error {
 	if p.Height < 0 {
 		return sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "height cannot be negative")
 	}
-	if p.Time.IsZero() && p.Height == 0 {
+	if p.Time.Unix() <= 0 && p.Height == 0 {
 		return sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "must set either time or height")
 	}
-	if !p.Time.IsZero() && p.Height != 0 {
+	if p.Time.Unix() > 0 && p.Height != 0 {
 		return sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "cannot set both time and height")
 	}
-	if !p.Time.IsZero() && p.UpgradedClientState != nil {
+	if p.Time.Unix() > 0 && p.UpgradedClientState != nil {
 		return sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "IBC chain upgrades must only set height")
 	}
 
@@ -54,7 +54,7 @@ func (p Plan) ValidateBasic() error {
 
 // ShouldExecute returns true if the Plan is ready to execute given the current context
 func (p Plan) ShouldExecute(ctx sdk.Context) bool {
-	if !p.Time.IsZero() {
+	if p.Time.Unix() > 0 {
 		return !ctx.BlockTime().Before(p.Time)
 	}
 	if p.Height > 0 {
@@ -65,7 +65,7 @@ func (p Plan) ShouldExecute(ctx sdk.Context) bool {
 
 // DueAt is a string representation of when this plan is due to be executed
 func (p Plan) DueAt() string {
-	if !p.Time.IsZero() {
+	if p.Time.Unix() > 0 {
 		return fmt.Sprintf("time: %s", p.Time.UTC().Format(time.RFC3339))
 	}
 	return fmt.Sprintf("height: %d", p.Height)